Error message at login
Each time I login to Nextcloud, this error message appears:
Could not load at least one of your enabled two-factor auth methods. Please contact your admin.
I believe this is because I had registered in the past a U2F device with the old version of the plugin. Apparently, the migration step to the new U2F+WebAuthn plugin doesn't perform a full cleanup so you need to also run this command on the server according to the plugin documentation:
$ php occ twofactorauth:cleanup u2f
All user-provider associations for provider u2f have been removed.
After running this on my home instance, the error message went away, and there was one less screen to click-through at every login.