Error 403 on random occasions

Getting the following error on random occasions since yesterday. It may be related to other issues I am seeing at the same time, such as the Spark pool suddenly not starting up and the splash screen getting stuck with 401 (unauthorized) error.  This is not related to our configuration of access. This has been working before. It also works when I try some times, and other times not. It seems completely random.

Azure Service Health is just showing green (as always).