What do I even call this?

This has happened to me once or twice. It corrects you when you type in the kun and it should be on, not vice versa. Isn’t the background pink when it’s a kanji though? That’s a tell. Or you could just by default type in the kun and always get the correction. This “policy” makes sense to me. We are learning Japanese after all. At any rate, I highly recommend [Userscript] WaniKani Katakana Madness It types in katakana for onyomi readings. I find it gives a gentle nudge of reminder and also helps prevent the atrophy of katakana proficiency from disuse.