Well, you probably broke something. This in a Mint 21 VM (sorry stock ubuntu 22.04 is too horrible)
This in a terminal
1) The regular 2.10.32 flatpak installed (and working) Followed by the 2.99 flatpak. The 2.99 starts by default.
2) I can make the first install Gimp 2.10.32 the default.
3) ...and that now starts Gimp 2.10.32. (ignore those error messages Gimp does start)
4) Without reverting back to making Gimp 2.99 default I can start it from command line using
flatpak run org.gimp.GIMP//beta
Do you really need to run both ?
This in a terminal
1) The regular 2.10.32 flatpak installed (and working) Followed by the 2.99 flatpak. The 2.99 starts by default.
2) I can make the first install Gimp 2.10.32 the default.
3) ...and that now starts Gimp 2.10.32. (ignore those error messages Gimp does start)
4) Without reverting back to making Gimp 2.99 default I can start it from command line using
flatpak run org.gimp.GIMP//beta
Do you really need to run both ?