Unfortunately this has been a bug since release that hasn't been addressed.
https://forums.playdeadlock.com/threads/rebinding-ping-button-stops-ability-cooldown-pings-from-working.43868/
Seems like a bug to me, everyone's mic is super quiet. I have people in nearly every game telling each other their mic is very low, it's a widespread issue. Voice slider at 100%. Mic sounds perfect in steam audio and any other application or recording. Only in deadlock is it very low.
After rebinding the ping button from Mouse3 I can no longer ping my ability cooldowns. I can still ping on the map using the new keybind, but pinging abilities does nothing. Reverting the keybind change restores the ability to ping cooldowns using Mouse3.