flatpak gives this info when updating. You might want to consider upgrading the runtime. (I don't know if there are major changes that make it incompatible)
Info: (pinned) runtime org.gnome.Platform branch 43 is end-of-life, with reason:
The GNOME 43 runtime is no longer supported as of September 20, 2023. Please ask your application developer to migrate to a supported platform.
Info: applications using this runtime:
com.hunterwittenborn.Celeste
Janybanny
commented
1 year ago
flatpak gives this info when updating. You might want to consider upgrading the runtime. (I don't know if there are major changes that make it incompatible)