I gave dark mode a spin, and generally really like it. However, I found that the suggested change feature in PRs is very difficult to read. It may be because I’m colour blind, I’m not sure, but it’s difficult to work with.
I have a screenshot of light mode, but I can’t post two embeds, so you’ll just have to take a look at the dark mode issue:
There’s just not enough distinction between the two blocks. It’s not super clear in the light mode, but it’s better than with the banded lines.