At this point I believe it's abundantly clear that there are issues with the audio drivers issued by Dell, and that as of this point in time, they have not issued any fix.
If this were to change, and someone has a link to a Dell supplied, official driver then please send a message containing same and I will approve it after checking. For the moment, though, this topic is on moderated status, which essentially means locked unless I were to receive something related to an official fix from Dell or something supplied directly by Microsoft or Realtek that would resolve the issue if installed.
Brian - Windows 10 Pro, 64-Bit, Version 20H2, Build 19042
If you think that you can think about a thing, inextricably attached to something else, without thinking of the thing it is attached to, then you have a legal mind.
~ Thomas Reed Powell