Too many simultaneous gnome-x-xx and core loop devices?

I have many simultaneous gnome-x-xx and core loop devices.

1. Why is that? Is each of them required by any currently installed snap app? What produces the installation of each of those snaps? As per "Types of snap" here, core snaps seem to be of type base, and gnome snaps seem to be of type app.
2. Should I remove some of them? I.e., in the current state of my system will I have any problem? How to tell which other snaps (installed or not) require each of them?
3. Can having them degrade performance of my system?

This is what I see

$ df -h
Filesystem      Size  Used Avail Use% Mounted on
...
/dev/loop0      128K  128K     0 100% /snap/bare/5
/dev/loop1       56M   56M     0 100% /snap/core18/2721
/dev/loop2       56M   56M     0 100% /snap/core18/2745
/dev/loop3       64M   64M     0 100% /snap/core20/1852
/dev/loop4       64M   64M     0 100% /snap/core20/1879
/dev/loop5      165M  165M     0 100% /snap/gnome-3-28-1804/194
/dev/loop6      165M  165M     0 100% /snap/gnome-3-28-1804/198
/dev/loop7      219M  219M     0 100% /snap/gnome-3-34-1804/90
/dev/loop8      219M  219M     0 100% /snap/gnome-3-34-1804/93
/dev/loop10     350M  350M     0 100% /snap/gnome-3-38-2004/140
/dev/loop9      350M  350M     0 100% /snap/gnome-3-38-2004/137
/dev/loop11      82M   82M     0 100% /snap/gtk-common-themes/1534
/dev/loop12      92M   92M     0 100% /snap/gtk-common-themes/1535
/dev/loop13      46M   46M     0 100% /snap/snap-store/638
/dev/loop15      54M   54M     0 100% /snap/snapd/18933
/dev/loop16      54M   54M     0 100% /snap/snapd/19122
/dev/loop17      74M   74M     0 100% /snap/core22/634
/dev/loop18      13M   13M     0 100% /snap/snap-store/959
/dev/loop19     461M  461M     0 100% /snap/gnome-42-2204/102
...

$ snap list
Name               Version                     Rev    Tracking         Publisher   Notes
bare               1.0                         5      latest/stable    canonical✓  base
core18             20230426                    2745   latest/stable    canonical✓  base
core20             20230404                    1879   latest/stable    canonical✓  base
core22             20230503                    634    latest/stable    canonical✓  base
gnome-3-28-1804    3.28.0-19-g98f9e67.98f9e67  198    latest/stable    canonical✓  -
gnome-3-34-1804    0+git.3556cb3               93     latest/stable/…  canonical✓  -
gnome-3-38-2004    0+git.6f39565               140    latest/stable    canonical✓  -
gnome-42-2204      0+git.587e965               102    latest/stable    canonical✓  -
gtk-common-themes  0.1-81-g442e511             1535   latest/stable/…  canonical✓  -
snap-store         41.3-71-g709398e            959    latest/stable/…  canonical✓  -
snapd              2.59.2                      19122  latest/stable    canonical✓  snapd

$ losetup -a
/dev/loop1: []: (/var/lib/snapd/snaps/core18_2721.snap)
/dev/loop19: []: (/var/lib/snapd/snaps/gnome-42-2204_102.snap)
/dev/loop17: []: (/var/lib/snapd/snaps/core22_634.snap)
/dev/loop8: []: (/var/lib/snapd/snaps/gnome-3-34-1804_93.snap)
/dev/loop15: []: (/var/lib/snapd/snaps/snapd_18933.snap)
/dev/loop6: []: (/var/lib/snapd/snaps/gnome-3-28-1804_198.snap)
/dev/loop13: []: (/var/lib/snapd/snaps/snap-store_638.snap)
/dev/loop4: []: (/var/lib/snapd/snaps/core20_1879.snap)
/dev/loop11: []: (/var/lib/snapd/snaps/gtk-common-themes_1534.snap)
/dev/loop2: []: (/var/lib/snapd/snaps/core18_2745.snap)
/dev/loop0: []: (/var/lib/snapd/snaps/bare_5.snap)
/dev/loop18: []: (/var/lib/snapd/snaps/snap-store_959.snap)
/dev/loop9: []: (/var/lib/snapd/snaps/gnome-3-38-2004_137.snap)
/dev/loop16: []: (/var/lib/snapd/snaps/snapd_19122.snap)
/dev/loop7: []: (/var/lib/snapd/snaps/gnome-3-34-1804_90.snap)
/dev/loop5: []: (/var/lib/snapd/snaps/gnome-3-28-1804_194.snap)
/dev/loop12: []: (/var/lib/snapd/snaps/gtk-common-themes_1535.snap)
/dev/loop3: []: (/var/lib/snapd/snaps/core20_1852.snap)
/dev/loop10: []: (/var/lib/snapd/snaps/gnome-3-38-2004_140.snap)

1. For gnome-x-xx, see this post, and for core loop devices, see this. They are preinstalled backends for to-be-installed snap apps (but the only snap app you seem to have is snap-store).

2. If you don't want to use snaps, it is safe to remove them. If you want to continue using snaps, let snapd decide what to keep, and don't mess with it.

To answer the last part of your question, in general, snaps affect the performance and startup time of your system noticeably unless you have a fast hard drive or an SSD. So, unless you really need a particular app which is not available without snap, get rid of snapd. Also, it may save you a few gigabytes of hard drive space.

From your snap list, it seems that the only application you are using is snap-store, which is the app store to install other snaps (so, if you don't use snaps, it is not necessary).

About your installed snaps - The core18/20/22 packages are like base Ubuntu images which snap apps utilize, the gnome* packages are GNOME backends for snap apps, and gtk-common-themes provide common GTK themes for snap apps. You don't need any of them if you don't intend to use snap apps, since apt versions of GTK theme and a version of GNOME is preinstalled in Ubuntu. Therefore, you don't need to replace them with anything.

Once snap store is gone, you may want to install gnome-software as a graphical package manager.

sudo apt install gnome-software --no-install-recommends

The --no-install-recommends ensures that it will not automatically pull the snap plugin.

By default, gnome software handles apt/deb packages. It can also handle snap and flatpak packages via the plugins gnome-software-plugin-snap and gnome-software-plugin-flatpak.