GIMP problems (on Linux Mint)

[FranzBias]

Hello everyone,
I'm new to the forum. 

I'm having some problems with GIMP 3.0.4 (Flatpak) installed today on my PC with Linux Mint 22.1 Cinnamon.
Until two days ago, I had version 2.10.36-3ubuntu0.24.04. However, since yesterday I have been unable to use it: when creating or opening an image, the various mouse cursors (brush, selection, etc.) remain confined to the left side immediately after the toolbar and there is no way to do anything. After searching in vain, I purged GIMP (sudo apt-get purge --auto-remove gimp) and installed the Flatpak version.

Now, these are the problems I have: 

1. When I went to Edit>Preferences>Folders>Brushes, I saw that there are 2 folders, but when I try to open them, it tells me that the folder cannot be found. The folders indicated are these:
   /home/franz/.var/app/org.gimp.GIMP/config/GIMP/3.0/brushes
   /app/share/gimp/3.0/brushes
   I went to check and, indeed, under the folder /home/franz/.var/app/org.gimp.GIMP/config/GIMP there was nothing, all the various folders were missing, i.e. there was no /3.0 folder and all the subfolders /brushes /filters /fonts /plug-ins etc.! So all the other various preference folders do NOT actually exist (!?); 
   
2. When I try to put a new brush in the brushes folder indicated by the programme (see above), it does not exist when I reopen Gimp. It should be noted that, since the folder did not exist (see point 3 above), I created the /3.0/brushes folder myself, but, as mentioned, even if I put new brushes in it, they are not recognised.
   
3. When I right-click on a layer, all the icons are missing from the list that appears. Have they perhaps been removed in the current version?
   

I think that's everything .

Thanks and best regards to all,
Franz