Yes, I have noticed about a recent changes in the facebook algorithem.
Boat dropping reaction march 2019 before.
As I see, Facebook has made lots of changes to its algorithm. I've found new reaction limits per account. I don't know (or not sure) if it is calculating the reaction speed based on the IP address (if the ip is rotative) or it's a general limit. (But looks like it's a general limit, triggered in some specific cases. ) My research points that if you execute the JavaScript from the main page, it doesn't get triggered (may it s a bug?).about 2 weeks earlier facebook blocked thousands ad accounts in Russia and it took about one hour (sorry for my english)