I don't know; I am not sure I'm marketable in THIS particular market.
As for FastAPI bring a mistake - that's an overgeneralisation to be sure. It has it's uses.
My first issue is that it falls into the same kind of small footprint as Flask. Every Flask project I work on slowly reinvents Django via a combination of plugins of varied quality and custom code/plugins. Get some Auth plugins, build step for manifest static files, add in Jinja2, grab an ORM like SQLAlchemy (or hopefully PeeWee), a migration system, test runners with fixtures/dB integration and rollback and on and on and on.
FastAPI is operating more at that level but also adds the often unnecessary complexity of async. In Python this is a cooperative setup meaning you have to yield to the event loop yourself (otherwise despite being "async" it blocks). Plus with a webapp all async often does is let you hammer your services (i.e. dispatch more queries to your poor DB) harder. The actual performance improvements don't manifest so much at scale as people often think. Plus you end up with a whole second set of ways to call functions and... makes me pine for gevent.
There are absolutely cases for this kind of async, even in webapps, but it's often not actually that helpful in places that it's used (and doesn't actually need to be everywhere). Good development imo means picking the right tool for the job rather than jumping on hype trains.
MongoDB is webscale!!