I just got into a competitive game and got disconnected for no reason (my internet was not dropped). Then I cannot join back the comp while I can actually join other games e.g. quick play, arcade and even another competitive game…
This is really stupid and I trust i got reported by everyone for.
I’ve seen so many people complain about this as it has happened to me as well. Absolutely stupid and I kinda don’t wanna play comp now because of it.
This just happened to me. It’s not even registered as my last game now. It’s completely off the record and my buddy was in the match and got a loss because of it. I don’t want to say I am the pillar of their gameplay, but I’m also not a liar. 
Pretty annoying to be booted from game though. I hope this gets fixed soon as I’d like to not be the cause or see someone else booted and being the cause of a win or loss for myself or others.
This happened to me too a few minutes ago. Hopefully they notice it and fix this soon. 
Linking my post in case you would like to read more about this issue Comprehensive Thread Of All Top 500/Competitive Bugs. I put your thread under: Competitive Match Disconnection And Temporary Ban.