https://github.com/realm/realm-js/issues/3985
Likely what’s happening is that if the device time is more than 30 min in the future, it thinks its access token is expired, so it requests a new one. But that one will also (immediately) appear to be expired too, so it tries again, etc. in an infinite loop. 
To mitigate this, the client could check if the newly minted access token is already expired. If it is, then likely there's an unrecoverable issue.