This is on Ubuntu 19.10, kernel 5.3.0, and it started happening after a minor update, so I figured it would probably get fixed in another minor update. That didn't happen, so then I thought I'd better update to a newer kernel before reporting anything. Then 20.04 was almost here, so I decided to wait for that. Hopefully I'll get around to that soon and discover my particular bug has been fixed, otherwise I'll try to report it.
You can try kernel-ppa [0] to see if it's fixed in newer kernels, it's very simple and you don't need to compile anything. I would recommend you to test 5.7 from there, and if that doesn't work you can try drm-intel-nightly or drm-tip: those are the upstream graphics trees. If you report a bug, the first thing the devs are going to ask you is test these trees, so it might be worth trying before you even open a bug report.
I got a bunch of warnings about missing firmware so I manually downloaded some i915 firmware files from the linux-firmware repo. I assume that's just an Ubuntu packaging quirk. I'm not sure if they were actually needed or not.