It might look that way to someone who's just recruiting, but if it got to the point where OP was burnt out, it's probably more than zero. 4 years isn't really that much, especially if they were using a relatively recent framework or something.
If they were building flask applications then, and refresh their memory, they probably already know how to become productive contributors on a team.
If they were building flask applications then, and refresh their memory, they probably already know how to become productive contributors on a team.