I don't think it's clear at all that you're having the same problem as described in this thread, especially since I don't think it was ever really clear what the problem in this thread actually was to begin with.
The description of this problem is quite similar to what I have, so decided that this is the same problem.
Hmm, it's turned out to be quite simple to reproduce this issue in a blank project.
Here is an example project attached. To check it, you need iOS device and a bit of patience. On my PC all works fine, on Android - I can't check it right now, but on my iPhone8 and iPadPro-2ndGen (both on iOS 14.7.1, testing by C3 Remote Preview) audio starts crackling (or pops) after about 2-3 minutes and then becomes harder and harder until all audio is messed up in noise.
Interesting moment - I also have a very old iPadAir with iOS 12.5.4, and on it - all works fine, almost no sound issues, just a few "pops" maybe in 5 minutes.
By the way, on the same devices (with iOS 14.7.1) I have my old game C2 build (compiled somewhere in 2017) that still works fine without this issue.
I will create a bug report with this example file, but not sure how it can help...
update: bugreport github.com/Scirra/Construct-3-bugs/issues/5063