It's just the routers web page is based off some older HTML code that using newer browsers and dark mode web pages, makes the older web pages appear incorrectly. Something you can try and see if it help some, set the flag for dark mode and set the mode to Enabled with selective inversion of non-imaged elements if you see that item there. Something I noticed years ago after dark mode was made available, web pages appeared dark however pictures, icons and gifs were inverted in negative display in the browser. I happened to stumble on this one item for this flag and after I enabled it, all items on the web page are now displayed correctly. Can try this, however may not help. Just be aware of older router web pages with dark mode features enabled.
