In the deck of “Duolingo - Japanisch” are cards with a false typing. Instead of the written りis shown リ, that makes no sense. I tried to correct it, but don’t find a way, see the screenshots:
Can somebody help? Thanks a lot!
Are you sure that’s not a hiragana ri? I haven’t kept up with my kana studies, but I seem to remember that character in particular can show up differently in different fonts. For instance, in your post, I see a similar ri to what you have on those cards.
On the other hand, if remembering wrong, and the correct character is shown in the Edit Note screen, but it is actually the wrong character in Preview/when studying the cards, then it seems like it must be a card template issue. For that, I would recommend getting in touch with the deck author.