pbkdf2 password on grub doesn't work on my Ubuntu 22.04 Vm

I installed a Ubuntu 22.04.3 LTS on a VirtualBox VM. After install process, I configured pbkdf2 as explained here https://help.ubuntu.com/community/Grub2/Passwords. I also verified grub.cfg after I ran update-grub, and it appeared correct. Anyway when the system boot, it doesn't ask me for any user/password, even if I don't use "--unrestricted" parameter. Here I paste my /boot/grub/grub.cfg :

# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
  set have_grubenv=true
  load_env
fi
if [ "${initrdfail}" = 2 ]; then
   set initrdfail=
elif [ "${initrdfail}" = 1 ]; then
   set next_entry="${prev_entry}"
   set prev_entry=
   save_env prev_entry
   if [ "${next_entry}" ]; then
      set initrdfail=2
   fi
fi
if [ "${next_entry}" ] ; then
   set default="${next_entry}"
   set next_entry=
   save_env next_entry
   set boot_once=true
else
   set default="0"
fi

if [ x"${feature_menuentry_id}" = xy ]; then
  menuentry_id_option="--id"
else
  menuentry_id_option=""
fi

export menuentry_id_option

if [ "${prev_saved_entry}" ]; then
  set saved_entry="${prev_saved_entry}"
  save_env saved_entry
  set prev_saved_entry=
  save_env prev_saved_entry
  set boot_once=true
fi

function savedefault {
  if [ -z "${boot_once}" ]; then
    saved_entry="${chosen}"
    save_env saved_entry
  fi
}
function initrdfail {
    if [ -n "${have_grubenv}" ]; then if [ -n "${partuuid}" ]; then
      if [ -z "${initrdfail}" ]; then
        set initrdfail=1
        if [ -n "${boot_once}" ]; then
          set prev_entry="${default}"
          save_env prev_entry
        fi
      fi
      save_env initrdfail
    fi; fi
}
function recordfail {
  set recordfail=1
  if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi
}
function load_video {
  if [ x$feature_all_video_module = xy ]; then
    insmod all_video
  else
    insmod efi_gop
    insmod efi_uga
    insmod ieee1275_fb
    insmod vbe
    insmod vga
    insmod video_bochs
    insmod video_cirrus
  fi
}

if [ x$feature_default_font_path = xy ] ; then
   font=unicode
else
insmod part_gpt
insmod ext2
set root='hd0,gpt3'
if [ x$feature_platform_search_hint = xy ]; then
  search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt3 --hint-efi=hd0,gpt3 --hint-baremetal=ahci0,gpt3  7533dc2b-102d-4445-b44b-ef6528f6be31
else
  search --no-floppy --fs-uuid --set=root 7533dc2b-102d-4445-b44b-ef6528f6be31
fi
    font="/usr/share/grub/unicode.pf2"
fi

if loadfont $font ; then
  set gfxmode=auto
  load_video
  insmod gfxterm
  set locale_dir=$prefix/locale
  set lang=it_IT
  insmod gettext
fi
terminal_output gfxterm
if [ "${recordfail}" = 1 ] ; then
  set timeout=30
else
  if [ x$feature_timeout_style = xy ] ; then
    set timeout_style=menu
    set timeout=10
  # Fallback normal timeout code in case the timeout_style feature is
  # unavailable.
  else
    set timeout=10
  fi
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/01_users ###
set superuser=admin
password_pbkdf2 admin grub.pbkdf2.sha512.10000.BAdXXXXX<etc>
### END /etc/grub.d/01_users ###

### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=white/black
set menu_color_highlight=black/light-gray
### END /etc/grub.d/05_debian_theme ###

### BEGIN /etc/grub.d/10_linux ###
function gfxmode {
    set gfxpayload="${1}"
    if [ "${1}" = "keep" ]; then
        set vt_handoff=vt.handoff=7
    else
        set vt_handoff=
    fi
}
if [ "${recordfail}" != 1 ]; then
  if [ -e ${prefix}/gfxblacklist.txt ]; then
    if [ ${grub_platform} != pc ]; then
      set linux_gfx_mode=keep
    elif hwmatch ${prefix}/gfxblacklist.txt 3; then
      if [ ${match} = 0 ]; then
        set linux_gfx_mode=keep
      else
        set linux_gfx_mode=text
      fi
    else
      set linux_gfx_mode=text
    fi
  else
    set linux_gfx_mode=keep
  fi
else
  set linux_gfx_mode=text
fi
export linux_gfx_mode
menuentry 'Ubuntu' --class ubuntu --class gnu-linux --class gnu --class os  $menuentry_id_option 'gnulinux-simple-7533dc2b-102d-4445-b44b-ef6528f6be31' {
    recordfail
    load_video
    gfxmode $linux_gfx_mode
    insmod gzio
    if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
    insmod part_gpt
    insmod ext2
    set root='hd0,gpt3'
    if [ x$feature_platform_search_hint = xy ]; then
      search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt3 --hint-efi=hd0,gpt3 --hint-baremetal=ahci0,gpt3  7533dc2b-102d-4445-b44b-ef6528f6be31
    else
      search --no-floppy --fs-uuid --set=root 7533dc2b-102d-4445-b44b-ef6528f6be31
    fi
    linux   /boot/vmlinuz-6.2.0-26-generic root=UUID=7533dc2b-102d-4445-b44b-ef6528f6be31 ro  quiet splash $vt_handoff
    initrd  /boot/initrd.img-6.2.0-26-generic
}
submenu 'Advanced options for Ubuntu' $menuentry_id_option 'gnulinux-advanced-7533dc2b-102d-4445-b44b-ef6528f6be31' {
    menuentry 'Ubuntu, with Linux 6.2.0-26-generic' --class ubuntu --class gnu-linux --class gnu --class os  $menuentry_id_option 'gnulinux-6.2.0-26-generic-advanced-7533dc2b-102d-4445-b44b-ef6528f6be31' {
        recordfail
        load_video
        gfxmode $linux_gfx_mode
        insmod gzio
        if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
        insmod part_gpt
        insmod ext2
        set root='hd0,gpt3'
        if [ x$feature_platform_search_hint = xy ]; then
          search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt3 --hint-efi=hd0,gpt3 --hint-baremetal=ahci0,gpt3  7533dc2b-102d-4445-b44b-ef6528f6be31
        else
          search --no-floppy --fs-uuid --set=root 7533dc2b-102d-4445-b44b-ef6528f6be31
        fi
        echo    'Loading Linux 6.2.0-26-generic ...'
        linux   /boot/vmlinuz-6.2.0-26-generic root=UUID=7533dc2b-102d-4445-b44b-ef6528f6be31 ro  quiet splash $vt_handoff
        echo    'Loading initial ramdisk ...'
        initrd  /boot/initrd.img-6.2.0-26-generic
    }
    menuentry 'Ubuntu, with Linux 6.2.0-26-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os  $menuentry_id_option 'gnulinux-6.2.0-26-generic-recovery-7533dc2b-102d-4445-b44b-ef6528f6be31' {
        recordfail
        load_video
        insmod gzio
        if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
        insmod part_gpt
        insmod ext2
        set root='hd0,gpt3'
        if [ x$feature_platform_search_hint = xy ]; then
          search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt3 --hint-efi=hd0,gpt3 --hint-baremetal=ahci0,gpt3  7533dc2b-102d-4445-b44b-ef6528f6be31
        else
          search --no-floppy --fs-uuid --set=root 7533dc2b-102d-4445-b44b-ef6528f6be31
        fi
        echo    'Loading Linux 6.2.0-26-generic ...'
        linux   /boot/vmlinuz-6.2.0-26-generic root=UUID=7533dc2b-102d-4445-b44b-ef6528f6be31 ro recovery nomodeset dis_ucode_ldr 
        echo    'Loading initial ramdisk ...'
        initrd  /boot/initrd.img-6.2.0-26-generic
    }
}

### END /etc/grub.d/10_linux ###

### BEGIN /etc/grub.d/10_linux_zfs ###
### END /etc/grub.d/10_linux_zfs ###

### BEGIN /etc/grub.d/20_linux_xen ###

### END /etc/grub.d/20_linux_xen ###

### BEGIN /etc/grub.d/20_memtest86+ ###
menuentry 'Memory test (memtest86+.elf)' {
    insmod part_gpt
    insmod ext2
    set root='hd0,gpt3'
    if [ x$feature_platform_search_hint = xy ]; then
      search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt3 --hint-efi=hd0,gpt3 --hint-baremetal=ahci0,gpt3  7533dc2b-102d-4445-b44b-ef6528f6be31
    else
      search --no-floppy --fs-uuid --set=root 7533dc2b-102d-4445-b44b-ef6528f6be31
    fi
    knetbsd /boot/memtest86+.elf
}
menuentry 'Memory test (memtest86+.bin, serial console)' {
    insmod part_gpt
    insmod ext2
    set root='hd0,gpt3'
    if [ x$feature_platform_search_hint = xy ]; then
      search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt3 --hint-efi=hd0,gpt3 --hint-baremetal=ahci0,gpt3  7533dc2b-102d-4445-b44b-ef6528f6be31
    else
      search --no-floppy --fs-uuid --set=root 7533dc2b-102d-4445-b44b-ef6528f6be31
    fi
    linux16 /boot/memtest86+.bin console=ttyS0,115200n8
}
### END /etc/grub.d/20_memtest86+ ###

### BEGIN /etc/grub.d/30_os-prober ###
### END /etc/grub.d/30_os-prober ###

### BEGIN /etc/grub.d/30_uefi-firmware ###
### END /etc/grub.d/30_uefi-firmware ###

### BEGIN /etc/grub.d/35_fwupd ###
### END /etc/grub.d/35_fwupd ###

### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.

### END /etc/grub.d/40_custom ###

### BEGIN /etc/grub.d/41_custom ###
if [ -f  ${config_directory}/custom.cfg ]; then
  source ${config_directory}/custom.cfg
elif [ -z "${config_directory}" -a -f  $prefix/custom.cfg ]; then
  source $prefix/custom.cfg
fi
### END /etc/grub.d/41_custom ###

I thanks in advance for any suggestion...