No solution, just comments
'buntu 20.04 default Gimp is 2.10.18 not 2.10.20 and looking at your script-fu folders list you installed the snap version of Gimp.
Generally that is ok, it does work (for most things) added scripts should go in ~/snap/gimp/292/.config/GIMP/2.10/scripts That works here for me. A script there runs on an open image in Gimp.
The installation folder might show as /usr/share/gimp/2.0/scripts but it is actually /snap/gimp/292/usr/share/gimp/2.0/scripts
You 'upgraded' to 'buntu 20.04 Does that mean over the top of your existing (maybe 'buntu 18.04) installation? I wonder are there bits of the old remaining? The old Gimp profile for example. Looks that way from your 'scripts' folder list.
In a terminal what does whereis gimp show?
Also in a terminal a plain gimp command works, a bit strange considering it is /snap/bin/gimp Gimp starts but I get the same sort of error message as you do. These 'snap' installations are sandboxed and self-contained. Might explain why the gimp - command - batch fails.
'buntu 20.04 default Gimp is 2.10.18 not 2.10.20 and looking at your script-fu folders list you installed the snap version of Gimp.
Generally that is ok, it does work (for most things) added scripts should go in ~/snap/gimp/292/.config/GIMP/2.10/scripts That works here for me. A script there runs on an open image in Gimp.
The installation folder might show as /usr/share/gimp/2.0/scripts but it is actually /snap/gimp/292/usr/share/gimp/2.0/scripts
You 'upgraded' to 'buntu 20.04 Does that mean over the top of your existing (maybe 'buntu 18.04) installation? I wonder are there bits of the old remaining? The old Gimp profile for example. Looks that way from your 'scripts' folder list.
In a terminal what does whereis gimp show?
Also in a terminal a plain gimp command works, a bit strange considering it is /snap/bin/gimp Gimp starts but I get the same sort of error message as you do. These 'snap' installations are sandboxed and self-contained. Might explain why the gimp - command - batch fails.