On Tuesday December 6th (around 6:00 UTC) there will be some emergency network maintenance performed in one of Unity’s facilities. This should have minimal to no impact on Cloud Build if it goes as planned, but there is a chance that (if it takes much longer than expected) it could ultimately affect Cloud Build’s capacity, as it would then interfere with Cloud Build’s connections to other internal Unity services - this could show up as failed or queued builds at that time.
That should be a very small risk, though; no direct impact to Cloud Build is expected.