We updated our site from 1.4 version to 2.0.0 beta 5. And this seems to change the redirect URL again to include a language prefix in it.
This breaks our currently login functionality because the return URL's have been configured without a language prefix.
There is an old issue #2911092: Remove language prefix from redirect URI → for 1.x where this was fixed. The previous fix was setting the URL to be absolute and as language none.
Closed: duplicate
2.0
Code
This seems to be a feature of D10 and there is an open discussion in ✨ Redirect URI has the language prefix in it (in D10) Needs review .