Firstly let me quote offical answer we got from another thread:
Driver engineering have looked into this and confirmed that it is expected behaviour for the memory clock of the 5700 XT to run at 875Mhz when using 144HZ refresh rate.
Only way to fix that issue is to dial back to 120hz or lower OR get rid of your AMD gpu and buy NVIDIA gpu. Since they managed to fix 144hz memory bug quite some time ago.
But dont worry it gets WORSE with every driver update. With latest drivers 19.12.3 i cant even watch a youtube video without gpu temps climb to 60C+. And the reason is: High memory clock. Keep in mind that im using my monitor at 100hz. Also i get weird buzzing noise from gpu if there is any movement on my monitor. Do fix that weird buzzing noise and high temps watching youtube i have to install pre 2020 drivers. Anyway this will be my last AMD gpu. What is the point of paying a 100EUR less and get broken thing if you can pay 100EUR more and get thing that works(talking about rx 5700xt vs rtx 2070S). All they do is add gimmicks to drivers that most people dont care about, instead of fixing bugs.