I've had this debate with someone recently, as soon as you actually want to use FastAPI/Flask in something that's not an internal only microservice, you end up building Django on top of it anyway ad-hoc way. It also ends up in more of a mess, because while Django doesn't enforce a code structure as such, the default way of doing things is fairly good.

The main thing I miss about Django is always the DB migrations in any case. I found that pattern to be very flexible and very powerful.