Roblox has been working on a new voice chat feature that you can take advantage of if you meet the right criteria.
What was originally created and developed as a beta in February of 2021 has slowly been distributed throughout the site over the last few months until now, in November of 2021, it has reached its finished product.
At the top of the Player List is also a "Mute All" option.
Try messing with this if you still can't hear or speak to other players.
While concerns are understandable, there is an age restriction and you can turn the feature off as well as report people.
If users do not meet either of these requirements, all voice chat features will most likely be disabled and restricted from their account.