His problem is poor anisotropic filtering (I have the same issue as the OP, with the same monitor resolution and I too run TS2020 “maxed”, yet suffer dreadful shimmering), and you have suggested he *lower* his AF settings?!?
That is going to make the problem worse.
The promlem is simple – TS only allows a maximum AF setting of 8x, whereas most games since around 2004 have allowed 16x.
That and – for me, anyway – Nvidia Inspector / Nvidia Control Panel is unable to “override” the AA/AF settings in game, since TS2018 (this was possible in TS2017 and earlier).