Encrypted install causes graphics glitching on Lenovo 470

This one boggles me. This seems to only happen when using Qubes on Lenovo 470 models ( possibly other types as well ) but not when Ive tested it on older Dell computers.

Steps to replicate: Do an install of qubes os with later than 3.0 version ( meaning 4.0 or later ) on a Lenovo 470 or other lenovo laptops.
Chose an encrypted installation.

After install and getting into the running system it will more or less randomly start to show pink lines from the bottom of the screen rising up and end up making the entire screen flicker and be messed up.
Using the off button on the computer to make it sleep then waking it again seems to often work to make the lines go away.
It will come back again after sometimes a few seconds other times half an hour or so. Most the time itll happen every few minutes. It does seem like using more ram or processor power will cause this to happen more frequently.

Can this be some frame buffer thing ?
Its not faulty computer as it happens on multiple different computers of the same type and only with the Qubes os 4.X
And as far as I can tell only if the drive is encrypted. I tried now installing it non encrypted and it works flawlessly so far.

What am I missing here ?

EDIT: I tried for fun to reinstall again this time with TPM 2.0 off. And it still works fine. It looks like its TPM 2.0 that is the problem. Ill try setting it back to see if the error persist. And then set it to TPM 1.2