I've made some complaints/observations on some other threads about this, because it's been happening to me.
 Your (OP) post brings up yet another idea - when becoming an 'original' partner, we were each explained that that designation put us in a different category in which we would have some preference over other videos. In other words, YT would help promote our videos.
 Now that virtually everyone can monetize (they couldn't before), and every single person who monetizes is considered a partner, perhaps the preferential treatment of being a partner is nonexistant now - or at least, extremely diluted.
 So maybe this is the new normal for many of us. WE had a slight advantage all along and it's gone now, and we're seeing the results.
 Just an idea I have.....