It seems like something has changed -- there are artifacts in all of these meshes, now. I've watched this for a while and this is relatively new! I've never commented using Observable before, apologies if this is not welcome

Interesting! I'm not seeing any artifacts, on Chrome / Mac at least — can you show a screenshot of what you're seeing, and perhaps additional details like what browsers this is reproducible in?

oh, this _is_ interesting. I tried more browsers and devices, first. The issue is something within my Firefox cached data or extensions. Signing out and clearing everything resolves the issue. it's definitely on my end, sorry about that!