It looks like a Dell-only problem.
I have a Dell 17" G7 Gaming Laptop 7790 with pre-installed Ubuntu 18.04 LTS.
However, if I remember well, the problem was not since the very beginning but started several months after I bought the notebook, maybe after some update.
Maybe the Dell proprietary modifications of Ubuntu 18.04 LTS very replaced by something in the generic Ubuntu update which created this problem.
I have a suspicion the generic Ubuntu does not manage to work well with some audio chipsets used by Dell, which is corrected with Dell proprietary fixes, but when these are replaced with generic Ubuntu updates, problems arise.
It looks like a Dell-only problem.
I have a Dell 17" G7 Gaming Laptop 7790 with pre-installed Ubuntu 18.04 LTS.
However, if I remember well, the problem was not since the very beginning but started several months after I bought the notebook, maybe after some update.
Maybe the Dell proprietary modifications of Ubuntu 18.04 LTS very replaced by something in the generic Ubuntu update which created this problem.
I have a suspicion the generic Ubuntu does not manage to work well with some audio chipsets used by Dell, which is corrected with Dell proprietary fixes, but when these are replaced with generic Ubuntu updates, problems arise.