Astigmatism is when every bright thing you see is copied multiple times with some offset in your vision. When it gets quite bad you can't see bright text because the offsetted one covers it completely and you can't read that either because there's more offsetted text that overlaps each other and it's a bit unstable too. When you use a light theme the background is the thing that gets offsetted but smh it can't completely cover the text but just makes it slightly grey instead of black