The login to the newer Fusion 360 version is now working again!
A way was found to deactivate the new login variant so that the old login method takes effect again.
This does not affect safety!
Only the functions with the Autodesk Single Sign-On (SSO) cannot be used, such as the link to a password manager app.
Many thanks also at this point here to the great community, who have been looking for possible solutions with me for many weeks and have sacrificed their free time to clear this serious bug aside!
And now let's implement wonderful projects with Fusion 360 on Linux together again!!!
Best regards from Germany
Steve Zabka