Yep, I'm still assuming its a bug rather than intentional as it doesn't work all the time..sometimes you can emote just fine, sometimes you can't, seems random. On PC.
I always felt some peeps are way too sensitive about emotes...they're just a harmless bit of fun, add some life to the game...so what if people use them ironically.
In my experience it ALWAYS happens now and its always the same couple of emotes blocked at the exact moment the game detects the match has been decided. Too suspicious be a random bug imo. I believe either the devs quietly made the change to appease "toxicity" whiners, or a single person/group within the devs made a hasty, secret change (which could explain why it seems like a bug and perhaps doesn't always work).