Now I have rebooted Mint 21.2, uininstalled GnuCash flaatpk 5.14, rebooted again, and when I tried to reinstall it, I get the error"While pulling app/org.gnucash.GnuCash/x86_64/stable from remote flathub: Writing content object: min-free-space-size 500MB would be exceeded, at least 1.2 MB requested" Oh well.