Backport PR #40143 on branch 1.2.x (REGR: reduction operations failing if `min_count` is larger)
Backport PR #40143: REGR: reduction operations failing if `min_count` is larger
> pandas/core/nanops.py:1373: error: Invalid type comment or annotation  [valid-type]

:-< @simonjayhawkins  we are using an older mypy on 1.2.x so this is expected. will fix up shortly.