Sorry to reply to this old post.
I confirm the flickering screen.
I always had the same issue when using LineageOS or even miui.
On android 13, it's much better but, lonce a week, it happen.
Since utouch halium for Poco X3 NFC is based on android 10, the flickering screen happens once a day at least. And when i use miui with android 10, i have the same problem everyday, so i suppose that it's not, technically, an utouch bug.