一期一会

TLDR: Do a touchscreen cable grounding, there's spots for it. Improve screen grounding. Do screen electronics shielding. You will need piece of wire, sticky copper tape, soldering skills and you should not try it if you're not have those skills!

The short story is I'm the lucky owner of the Lenovo Tab M10 Plus 3rd Gen android tablet, and this type of tablets (and as far as I know also some P-series tablets) have a touchscreen issue that appear after 1-2 years of not very active usage. First occurrences look like skipped touches or swipes, usually anywhere but not on the center of a screen. Later on, it will progress into almost unusable state where touchscreen does not pick any touches at all, but if you will hold your finger for a little bit more - it will eventually pick, and whole surface will work follow your finger swipe as long as you swiping, and will become into unusable state again right the moment you stopped touching it. Quick fix is to switch screen off/on with power button and it will start picking your touches immediately, until next random moment comes.

First of all, I thought that this is a software issue, because it often correlates with CPU/GPU load, but sometimes it's not. Re-flashing with custom ROM makes its response better but not that significant to make it use. I saw one guy did display cable shielding and it worked for him. I did it too, and it worked for me for a month, and then the issue returns. Looks like an electrical connectivity thing, isn't it? While you open your device, dance around the cable, you move things a bit and some connections fixed themselves.

Actually, what you have to do:

1) Remove a SIM/Card slot. Use something slim to try to detach screen part from a body part right near the empty sim slot (sim slot hole is on body part). When it cracks a bit - use any plastic card to insert into that crack and go around the tablet to split it in half. BE CAREFUL to not rip apart your display cable when you split things and decided to finally look what's inside as it too short. 

2) As far as you opened your device - you have to detach display cable. Do it from both sides and put apart. You will solder ground wire later. On a display part you have to unlatch connector (latch is on the opposite side from a cable).

3) Also, you will notice sponge-like metal-coated things around the main board which should do grounding across the display back part. Look at the display part and you will notice that those sponge-like things lost some glue on the metal shielding of a display. Scratch those spots with some sharp metal object to make it conduct your grounding lot better, then wipe off any glue residue.

4) You have to shield a display board with a copper tape. Put it right on top of a black factory tape. Be sure your copper tape touches metal display cover firmly and have 100% contact with it (use multimeter to check). I've used slim stripes so had to solder all the lines between each other on their ends.

5) On the display cable back side, you will notice two shiny grounding spots that was grounded onto display casing with a sticky metal-covered piece of fabric (that is obvious conduct nothing). You have to solder piece of wire to a longer spot and to your common ground which you've just done in a previous step.

6) Do final check with a multimeter, and if everything is connected firmly - connect cable back, close your device and try. It's done.

Here is some visual:

Have fun.