Fedora 35 dnf ignores max_parallel_download in /etc/dnf/dnf.conf

maybe a stupid question but I couldn't find any good hint of what went wrong.

Except for this Post - but unfortunately, it is a dead end. ;-(
Why DNF is not obeying "max_parallel_downloads" from config file?

I am using Fedora as Workstation Version as well as Server with a local mirror.

PRETTY_NAME="Fedora Linux 35 (Workstation Edition)"

Version of all DNF packages is the following:

[terpentin@mainsystem ~]$ rpm -qa |grep -i dnf |sort
dnf-4.9.0-1.fc35.noarch
dnfdaemon-0.3.20-7.fc35.noarch
dnfdaemon-selinux-0.3.20-7.fc35.noarch
dnf-data-4.9.0-1.fc35.noarch
dnfdragora-2.1.0-5.fc35.noarch
dnfdragora-updater-2.1.0-5.fc35.noarch
dnf-plugins-core-4.0.24-1.fc35.noarch
libdnf-0.64.0-1.fc35.x86_64
python3-dnf-4.9.0-1.fc35.noarch
python3-dnfdaemon-0.3.20-7.fc35.noarch
python3-dnf-plugins-core-4.0.24-1.fc35.noarch
python3-dnf-plugins-extras-common-4.0.15-2.fc35.noarch
python3-dnf-plugin-system-upgrade-4.0.15-2.fc35.noarch
python3-libdnf-0.64.0-1.fc35.x86_64

dnf.conf is set as follows:

[terpentin@mainsystem ~]$ cat /etc/dnf/dnf.conf 
[main]
gpgcheck=1
max_parallel_downloads=10
installonly_limit=3
clean_requirements_on_remove=True
best=False
skip_if_unavailable=True
deltarpm=false

I have this problem on all Fedora systems, so maybe the conf is wrong but the man page only said

   max_parallel_downloads
          integer

          Maximum number of simultaneous package downloads. Defaults to 3.
          Maximum of 20.

So nothing really could go wrong...but still, the default value is active.

Any advice?