GuzzleHttp Multiple Errors on hosting capabilities check

Despite I have followed all documentation and I have the “Nextcloud selftest” marked green I have log flooded continuously by this error

GuzzleHttp\Exception\ClientException: Client error: GET http://localhost/nextcloud/apps/richdocumentscode_arm64/proxy.php?req=/hosting/capabilities` resulted in a 403 Forbidden response: 403 Forbidden

Forbidden (truncated…)`

It looks like this request is considered a security violation.
Is there some exception that needs to be added in firewall or some specific configuration to fix this, or it is a bug?