Messing more with it, it seems to be related to the combo of sRGB being less bright/contrast than the non-sRGB modes, thus not enough to see the dots...

Zooming in (ctrl-wheelup) on the page causes it to disappear after the dots scale to the next size. Friend pointed out I can disable and test the css, which I did. I scaled to 2, and it's gone. So it's a scaling issue.

Then tried Vivaldi, same thing, turns out, it's gotta be a scaling issue with KDE/Kwin. It also only does it with 1440, not on 1080 (or 900, which I also tested). They're all 16:9 so it must not be a fractional scaling issue, maybe density just gets weird or it's the monitor in combo.

I have no idea whey I'm sharing just found it interesting in case anyone else wonders or notices.