from bug 1225654: http://codepen.io/Beclamide/full/bNyxVz/
Lines should be thinner, softer and not flickering. It looks good in Chromium.

Mozregression gives this range

I can also reproduce the flickering in Nightly93.0a1 Windows10.
Regression window(from cached build):
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=a0d10a7e5c3f219e8346667b107cb02506cbbdd8&tochange=0356e5fff183afb22f6eeca0e53ab8ec56745fad

Suspect: Bug 1559861

Seems potentially a snapping issue. Glenn, do you understand why bug 1559861 might have caused this?

It's not clear to me without some further investigation, but it's probably also not too surprising if it's a 3d transform. I know that we have some issues with how we incorrectly snap (or rather, don't snap at all) if there is an off-screen surface involved, which sounds like it would be the case here. It's possibly also related to the scale factors that end up being chosen for this 3d surface, which might be why mozregression pointed to that bug.

Set release status flags based on info from the regressing bug 1559861