This incident has been resolved. The "CPU and Memory" usage indicator in the top menu bar of JupyerLab remains disabled until further notice.

We have disabled the "CPU and Memory" usage indicator in the top menu bar of JupyerLab to mitigate the issue. We continue to analyse the issue.

We are currently investigating this issue.
Users with a valid and active JupyterLab session are seeing an intermittent popup notification "Server unavailable or unreachable" and prompting to 'Restart' or 'Dismiss'.
When selecting 'Dismiss' the page is refreshed and the instance appears to be working.