Yup, their contrast on a lot of elements is already way too low and this isn't helping. And light mode is honestly worse for accessibility on Discord because the vast majority of their base use dark mode and make choices for things that only work in dark mode. Like having a bright yellow for your username, it looks great against the dark grey background of dark mode, but is completely unreadable on the white background of light mode.
Hard to forget the bit where they removed Light Mode as a "joke". Very funny until you remember that many people can't easily use Discord in Dark Mode (in part because of how poorly Dark Mode is designed for accessibility) so you're sabotaging their experience as a gag.