Ah right, I missed your thread. Good catch

Thanks for looking into it!

If it's of any use, the dark mode plugin (https://github.com/tefkah/zotero-night?tab=readme-ov-file) which has now ceased development thanks to zotero's native dark mode had fairly good color fidelity for highlights in dark mode

That's true! It's also how some other pdf readers (eg adobe) handle dark mode highlights. I hadn't registered it as "different" because I sort of assumed that was how it ought to be handled for colour fidelity in dark mode.

I think I would prefer it to have the same colour and highlight it by colouring the text, as opposed to having different colours and not the highlight border. Or at least have it as an additional "third" display option.

The problem as I see it is that text is white in dark mode, which means that if the actual highlight is given its original colour, the output is unreadable because white text doesn't contrast with light colored highlights. Readable+accessible text rendering should have a strong contrast between the background and the text.

One way to sort this out is to render highlighted text in black, but let unhighlighted text retain its current white colour in dark mode.

Another option would be to use the coloured text option, but show the actual highlight as a border around the whole highlighted text.