This means that this profile has been used by a newer Firefox, in your case you likely have started the DE version with your release profile or currently you try to start the release version with a DE version.

To verify this you can check the compatibility.ini file in each of the profile. Firefox only warns when you try to downgrade a profile, but doesn't notify you when you use a profile with a newer version what will upgrade this profile. You can remove compatibility.ini to make it possible to reuse this profile in release or use the -allow-downgrade command line switch, but it isn't guarantee that this profile will function without problems with the release version. If you use DE and release with their own dedicated profile(s) then this should work without problems. If you choose other names then there can always be issues if you depend on the Profile Manager.

Thank you. That adding allow-downgrade to the shortcut path allowed the profile to be opened in release. I do use dedicated profiles between release and DE.

I'm not sure why this happened. I have separte icons and shortcuts for the DE but had none for releas., which always went to Profile Manager. When I added the shortcut with the profile name, perhaps something opened that I didn't notice, such as you described in your first paragraph and that cuased the issue following the update. I didn't notice but cannot say for certain.

Anyway, thank you for your assistance.