Hello
There is an essue with the multitouch in the touch screen
It seems that it can't take more than two fingers, if I put the third finger the previous two finger disappear, first noticed it in a piano app then I have tested it with many touch screen test apps (multitouch tester, multitouch test, device info...)
Some times it takes upto 5 fingers but it still glitches right away
However trying to understand the problem better I found that it is not a hardware problem since if you enabled developer options and then activated "show taps" and "pointer location" it shows all the fingers without any problem or any glitch (just for where it displays the touches graphicaly, the system still will not respond to the touches correctly, if I activated pointer location and then tested it with an multitouch test app the location demonstrated by the "pointer location" -developer option- shows correctly but in the multitouch test app the problem persistes at the same time)
Hope you help me solve this problem, I'll be thankful..

I shot a video about the problem but I don't know how to post it here
However I was doing some search on the internet and I found that the problem can be solved by disabling the three finger screenshot gesture

Go to Setting -> gestures and keys -> gesture motion -> system motion -> you need to disable all three (three point screenshot, three point entery camera, two point adjust volume).

After disabling all these the problem is gone and the multitouch works perfectly.