Small reminder for anyone who doesn't read fully (or at all) release news yet is using our #nightly #flatpak for testing latest code: you need to uninstall then reinstall the nightly flatpak with the commands given in the RC2 news:
https://www.gimp.org/news/2024/12/27/gimp-3-0-RC2-released/#flatpak

If you don't do so, you will be stuck on an ancient build without ever getting an update since we changed the AppID (it allows to see both stable and nightly versions side by side in your desktop).