I was able to reproduce both issues, thanks for reporting!
The proxy auth cookie secret is not persisted. It's stored in platform runtime data. I have migrated this into the database.
Redirection logic was incorrect when the token is invalid. This is also fixed.
@savity you have to reboot the server using your VPS control panel or "reboot" via SSH. Do not use the reboot button in Cloudron dashboard, it doesn't work. We will make a new release most likely end of this month (6.4) where it will get fixed.
@girish Yes, it does appear to pass the correct credentials, and the function in question seems to give no error. I'll try to debug further on the app side, but for now I think we can just file this as an unexplained weird thing 🤷