[Bug]: Log spammed with untrusted federated servers

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

Logging requests of untrusted servers as error can lead to a spammed log.

Steps to reproduce

I don't know, but I'm guessing

1. Federate two servers
2. Stop federation on one server

Expected behavior

Graceful handling, like a log warning

Nextcloud Server version

31

Operating system

None

PHP engine version

None

Web server

None

Database engine version

None

Is this bug present after an update or on a fresh install?

None

Are you using the Nextcloud Server Encryption module?

None

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

List of activated Apps

Nextcloud Signing status

Nextcloud Logs

Additional info

• https://github.com/nextcloud/server/issues/3372

Begin with the related issue #3372 and trace the federation request path that produces the reported error-level log. Establish a reproducible case for a stopped or untrusted federated server, identify the current severity and any relevant logging tests, and consider the work done when repeated requests no longer spam the log at error level.