Rounded edges pixels artifacts on dock and widgets (Mac mini late 2014)

Hello,

I have a Mac mini late 2014 on Mac OS Monterey 12.2.1 and not so long ago (I think after the update from Big Sur) I started to have some artifacts on the rounded edges of the dock, widgets and control center folders (see pictures).

I already tried to reset NVRAM and SMC multiple times but no results. I also performed a fresh reinstall with an external usb but nothing.

The problem doesn't seem to be my external monitor because there is still the problem on another one or on my TV (1080p or 4K) and even by using airplay (so even the HDMI isn't the problem).

I found the same problem here but there is no solution (My accessibility settings are by default):

Visual artifacts on rounded edges of Dock… - Apple Community

I think the problem came when I switched from Big Sur to Monterey. Do you have an idea of what could I do more ? Thank you in advance !