I have the same issue too (But with my left trigger). I read this post 1 day ago but I found a temporary "fix" and it's been working pretty well after a few hours now so I don't know if it will return. I'm not sure what it is that fixed it but one thing I noticed is that, when I set the trigger sensitivity from 3 to 1, it made it more responsive for longer on COD Mobile before the left trigger started to flicker again. Shortly after that, I drained my phone to 0% (Probably the first time I've ever done that on this phone considering that the battery life is excellent for me) and after I charged it up to 90%, I fancied another game of COD mobile hoping that the issue would randomly go away, and it's been working flawlessly even after an hour. Hopefully this will help, I'll try setting my setting my sensitivity back to 3 again to see if it still works well, but I've found myself getting used to playing with high sensitivity.