If you look in your trace logs in Google Cloud Run you may see the following trace, which may return errors with a code of 500.
If this does happen to you do not panic. These do not indicate an error in your application.
Rather these are internal calls that Google makes as signal messages in their architecture. This is why you will not see them in the Logs but only in Trace and why they are marked as healthy messages.
Even though these are harmless requests, it might be a good idea to keep close watch on these, as it may indicate an underlying problem. If these become too repetative in may be contacting the support team for help with the matter.