Other than the issues reported with the voice chat here: https://steamhost.cn/steamcommunity_com/groups/L4D2WSVB/discussions/0/846946775311116238/ there's also a voice chat issue in the lobby, voice chat doesn't work at all in the lobby (the mic icon appears but you can't hear anyone). If it's not going to be fixed I suggest you delete it from the lobby because some people are talking to themselves in the lobby without knowing.

You can only mute people in the lobby but there's no easy way to mute people in-game, what about a votemute (like votekick but instead it's votemute). It would also be great if you were forced to press "Yes" or "No" after you've selected a player's name (to votekick that person) because sometimes you choose the wrong name in the list (it's easy to missclick).