The previous bug was about dark to light controls, but I wasn't aware of any invisible text.

By the way I'm facing similar problem on the Desktop - I'm using black theme on my openSUSE and my controls in the browser are dark gray with black text. This is due to the browser using specified colors by default. You can switch system colors but it gets worse - many sites are setting the background and not the color of the text and it becomes light gray or white on white... So I suspect your problem is due to the same feature/setting.