Small piece of feedback: Why is 藤 introduced in level 22 without its onyomi? This isn’t a very common word or kanji on its own, but it’s frequently employed in names (I’ve met several -藤-named people recently), where it always comes with the とう or どう reading.
Even the notes on the kanji in its introductory lesson note that it’s mainly used for names, so why is the more practical reading held off on?
This kanji is most commonly used in names, so you can remember that by keeping in mind that it’s not a very commonly known flower, and people want to have unique names so they use this kanji in them or something.
Food for thought. The onyomi probably comes up at later levels, but it seems weird to include an admitted “mostly for names” kanji without immediately giving you its most common reading for that purpose.