I can't reproduce this on any of my devices, so I can't effectively investigate it. But I suspect that it's a recently-introduced bug in Chrome's hardware-accelerated rendering. Disabling hardware acceleration might fix it; maybe chrome://flags/#disable-accelerated-2d-canvas ? (NeuroticFish reports this isn't it)

If anyone can figure out exactly what causes it or whether I can change anything on my end to fix it, let me know.