Bots aim too well with nearly invisible players mutator
It happens on Level 21 of the Mirio's Singleplayer Campaign.
I actually have two issues with this level.
One - the nearly invisible players mutator here makes is ridiculously hard, much harder than previous levels. I've beaten the Oilrig deathmatch after a few hard tries, but after a few hard tries here I'm still at the very bottom of the scoreboard, with no hope I'll improve. I can't see almost anything once I start firing, and bots seem to do just fine, kicking my ass regardless.
So I'd suggest disabling the nearly invisible players mutator here, OR making bots aim much worse in these conditions, because they just hopelessly obliterate me on this level and I don't think I'll ever be good enough to beat it, unless I force fullbright models and disable all particle effects. And I don't think it's the point of the singleplayer campaign :)
Maybe some calibration matches should be done with identical settings, just turning the nearly invisible players on and off to balance the bots aiming to make the player feel equal. I guess it should alter the gameplay, not make it 8 times harder. It wouldn't work this way fro real players.
The second issue I have is that picking up a new weapon (also for bots) plays this "New toys! New toys!" voiceclip, that could be fun if heard once, but as a constant background noise - it's quickly getting very annoying. I don't actually think it adds anything special to the game. I get excited to use new weapons anyway, and it doesn't feel professional, like most of this game feels. So I'd suggest either throwing it away, or playing it once per match maximum.