iCloud Mail is experiencing an ongoing outage

I am one of the unlucky folks, my iOS mail client shows "weak consistent" list of emails, sometimes I do see a new email coming in but after refresh it vanishes from the list.

The iCloud Mail webpage no longer loads / load with a blank 3 column page, then a reporting error modal pops up:

" ENVIRONMENT INFO PROD

REPORTED ERROR TITLE Startup Failure: Unable to fetch messages (INVALID RESPONSE SHAPE)

REPORTED ERROR TYPE CANNOT_LOAD_STARTUP_DATA

LINE NUMBER Unknown "

Interesting, I've never seen this status page before.

  Some users are affected
  This service may be slow or unavailable.

I'm using iCloud Mail for my personal domain and haven't seen an interruption so far.

Would be interesting to know what happened.