The biggest issue I have with Duolingo is that they offer "grammar notes" to explain why specific elements are the way they are... but only on desktop web. In-app, which is the main way that I (and I'd imagine most users) use Duolingo, there are no grammar notes and no way to access the grammar notes - they just seem to assume that you'll pick it up from context. Personally I've been studying Russian, a language with extremely complex grammar much of which has no analogue in English or Spanish (the two other languages I speak), and were I not supplementing Duolingo with a textbook that actually explains the grammar, I would be extremely confused.
I really can't understand why they don't provide the grammar notes in their mobile apps. If it's trivial things like table rendering then I'm sure they can come up with something. It's such a crucial part of learning another language and it's completely ignored.
Grammar in general is my definitely my biggest issue. I have a firm grasp on grammatical terms in English, and it would be much easier for me if the rules of grammar were simply explained instead of implied.
I've found I end up looking at the comments frequently and just hoping that someone was kind enough to plainly explain the grammar at some point. Failing that, I end up asking fluent Spanish speakers random questions like, "Are adjectives gendered and pluralized in Spanish?" Which works up to a point, but when you start asking about things like "gerunds" and "past participle" you end up having to explain what those things mean in the first place (using English) and then ask the question again about Spanish.
Would love to see an app that focuses less on implied methods of teaching and is more willing to dive in to grammar lessons.
Yeah it makes no sense, a read more button that sends you to a screen that is basically just a text box with the notes would be enough. It has been requested for years on their forums.