Well, for me miui 11 fixed it. It surely looks like as a bad drivers issue. If it was hw it would never be fixed by sw and as far as I know, miui 11 fixed ghost touches issue for a lot of ppl. Even if miui 11 didn't solve the issue for a lot of other ppl, it doesn't discard it being a sw thing, because as we have different kind of display, drivers can be conflicting or a line of code that works for fts may break the other etcetera.
ofc it should never happen or xiaomi should have recognized this problem earlier and solved it faster, but after flashing miui 11 and now in Validus OS, ghost touches are really gone here.
I'm not discarding that can be hw issue too, but I rather not switch display when I know software can solve it.
PS: when I bought poco, it didn't have any issues with display (march this year). One the updates in fw that included this problem, which really leads me into thinking of it as bad drivers issue