Ever since I downloaded and installed MW2 Campaign, the sound on TS has been very low. I have turned every ones mic up to max and the TS is not a loud as it was in Vanguard.
I cannot hear Sunny, Kev is soft have to strain to hear him and Stainless, Snap I can hear well. Anyone else come across this and have a fix for it?

I have had no issue. Is this only while the game is running or even in vanguard now

  It happened after I installed the game. I think some others have the same problem. I don't about Vanguard yet, haven't played it with anyone else yet. Thank you for the reply Mr T

I have not purchased/installed MW2 yet but I have similar problems in TS when playing Vanguard (multiplayer). When the match starts it cancels all functionality to the Caps Lock key, which I use for PTT in TS. When match is over and we're back in the lobby it works as normal again. Strange....
Although, I haven't been in TS lately when playing e.g. Cold War, so it might not be specific to Vanguard in my case.
A daring suggestion: see if you who have the problem can meet up in our Discord for a quick game. Maybe that will tell you if the problem lies with TS or CoD.
Good luck!

viking that caused by having the caps lock key assigned to something in the game, go through all the keybinding and look for where caps lock is set (also check in the show more sections) by default it was show tactical map.

Max for audio levels make sure that all you audio setting in windows are correct, for example if selected headphones for your sound in game it have have adjusted the audio levels down to prevent hearing damage

I did check the key bindings earlier and found nothing.
However, as much as it pains me, I have to admit I had missed one of the expandable "show more" menues (Tac Map).
So, thanks for the tip, Mr-T. Now it will probably work again.