After my iPhone 11 on iOS 17.6.1 upgraded the official Bitwarden app to version 2024.8.1 on Saturday 7 September 2024 I can no longer sign in to my self-hosted server.
I checked I had the latest version of Vaultwarden server (which is last month - Releases · dani-garcia/vaultwarden · GitHub), then deleted the app from my phone and turned off the phone. I then restarted the phone, reinstalled the app and logged back in to my Vaultwarden self-hosted server fine.