The new format is hard to use on an iPad. The text is too spread out to fit the screen.
I read earlier today (not by a user but by the people who actually work for Duolingo, if I find the link again I'll tell you) that Duolingo is working on improving how it looks on medium sized screens (eg. tablet). Hope this helps.
Planned but low priority:
Improve how the site looks on medium-sized screens (e.g. tablets)
I had the same problem. One workaround is to open Duo in a browser. I use Chrome on my old iPad 4 and it works fine.
Duolingo wants you to use their iPad app on your iPad, not the website.
I downloaded the iPad app at one point. It appeared to be designed for school children, so I let it go.
While I'm often amazed at the poor choices that Duolingo makes on the website, it has to be said that part of Duolingo's approach to learning a language is to learn it the way a child learns it. Children are taught grammar, they figure out the grammar as they learn the language. Duolingo tries to imitate that approach, by exposing you to vocabulary and grammatical structures in a staged and repetitive fashion, but without actually laying out the grammar rules before you encounter them. And it is, by and large, fairly successful in that regard.