This has been addressed and it is not expected to resurface.
Underlying issue has been an expired root certificate (on Sep 29th) and some browsers operating on looser certificate caching rules (relying on the old instead of downloading the new one).
Issue would have apparently worked itself out on most devices in a few days and could also be addressed by clearing the os or browser certificate cache however…
…We’ve issued new certificates and enforced stricter certification chains, thus currently all our test devices operate as expected.
Thank you all for promptly reporting this and sorry again for the service disruption.