Ah, je comprends mieux Et tu es sur quelle distribution ?
je ne sais pas si ceci pourra t'aider (vu là : https://askubuntu.com/questions/1349179/how-to-install-a-previous-version-of-gimp-with-flatpak-on-ubuntu-20-04) :
Installing older flatpaks versions
You can install older versions of a flatpak by specifying a specific commit to target. Available commits can be found by using the remote-info command. You need to already have the flatpak installed for this to work. The older version takes place of the newer one, since you are performing a downgrade.
The results of remote-info are not a complete history, as there appears to be a cutoff point for versions kept. Because flatpaks are used to make it easy for developers to push the latest versions of software, keeping everything would not be so easy on storage space.
# examine remote
flatpak remote-info --log flathub org.gimp.GIMP
--snip--
Commit: c53c42d04e88c0b0c416d5b4d3aa7600d1cdbdcd36d051b1af5c4ae980e29bb2
Subject: Build Little-CMS 2.12 ourselves. (13d146e6)
Date: 2021-03-29 16:33:51 +0000
--snip--
# install specific commit
# root privileges required for system
flatpak update --commit=c53c42d04e88c0b0c416d5b4d3aa7600d1cdbdcd36d051b1af5c4ae980e29bb2 org.gimp.GIMP
# to prevent future updates, you can mask the flatpak
flatpak mask org.gimp.GIMP
The commits from the flatpak remote-info --log command cannot be substituted with the commits from GitHub as I previously thought. The GitHub commits are referenced in the output (13d146e6) in the above example but are not the ones used for moving between versions.
flatpak tips and tricks