I just got the same thing.. I got no warning or notification. I got to know about this when my articles weren't showing as isntant articles anymore.. This happened just a few hours back.. I sent an appeal and they replied back in 10 minutes saying -
"Thanks for submitting a request. You are currently eligible for monetization."
Even then it shows I have lost access to Instant Articles... I really don't know what to do.. I earned a bit in this month of May.. will I get the payment next month or is the money gone?.. I didn't even violate any thing, I am running pages no strikes nothing... Instant articles help me financially and if it's gone I don't know what to do... Can anyone please offer some insight..