perhaps this is the windows scaling issue?

this happens on windows, if the system display/scale setting is set to greater than 100%.
it results in viewport renders being rendered pixelated, regardless of AA settings.
if you render to PV, you don't see/get this.

(see png) https://drive.google.com/file/d/1iz3Dsd9D4VFN7Yi3loF6r27wDOwsLSz7/view?usp=drive_link
(standard render : AA @ 2x) should not look like this, but it does.

This started happening several versions back. I did report it.
you won't see it on a mac, and you won't see it on win at 100% scale.

best
Paul