I HATE dark mode in browsers. it makes everything funky like that, even DDG search gets on my nerves.
Here's what doesn't work: an app or extension that forces dark in internet dealings. Poorly.
What does work: most of the time a website's own toggle, like Solus' where I have no problems in dark.
I think it has to do with dark integration vs. strongarming and forcing dark.
Maybe I'm crazy.
It's not perfected, except for solus and my personal email, I don't do dark for anything anymore. rendering makes me bezerk. your weblink wasn't horrible but I didn't want to read it, either.
Short version: I surf mostly all light mode but mitigate this by dialing down budgie night light to pretty warm. So what's working for me is really subdued white vs. forced dark (solus and zoho excluded). 2 cents
edit---great observation. this is a relevant question you ask as we all spend probably too much time in front of screen
second edit: I only use FF and Chromium (inside) basically