lost featured offer on my all listings

I have lost the Featured offer / Buy box most of my products. Suddenly the the buy box of all of our FBA product I recommended has disappeared, and I don't know why. I continue to send goods and maintain good account health. I would greatly appreciate it if Amazon could send my case to the featured quotation team and please reply to me. Normally Prime products gets buy box but since last month cheapest one ate getting buy box. I am talking about all the items which i send to fba.

@Spencer_Amazon @Winston_Amazon