Hi Tom,
The "ghost touch" phenomenon is caused by electrical noise on the signal lines from the touch screen to the motherboard. This is almost always caused by damage or disruption of the delicate connections between the flex cable and the glass that the digitizer circuits are printed on.
Unfortunately there is no fix for the problem; the only way to cure the issue is to replace the screen assembly, which includes the AMOLED display and the digitizer fused together.
iFixit, sorry to say, doesn't have a guide to that repair, but the Spanish site Nadie Me Llama Gallina has one for the M4 Pro - it doesn't specify that it covers the 5G model, but it's the closest I could find for you.
[link|https://www.nadiemellamagallina.com/en/manuales/smartphones-1/poco-1304/poco-m4-pro-1325/pantalla-completa-11955|Manuals / Poco M4 Pro / Full Screen - Nobody Calls Me Chicken]