I have a Windows PC and I use high contrast mode due to vision issues. I didn't use dark mode in Firefox because before the last update, colour inversion was applied to Firefox automatically, but it turns out that doesn't actually matter, since enabling dark mode makes no difference to the problem I'm experiencing. Since the most recent update (which was only applied for me this morning), every website I visit is in forced light mode, including the landing page. As mentioned above, turning on Firefox dark mode makes no difference, nor does turning on dark mode on the websites I'm visiting, if available. The header and URL bars are still dark, and some websites have some black boxes here and there. I can't read text on a white background, so Firefox is unusable for me right now.