In #10319 a fix was introduced to correctly calculate mean for boolean arrays. Unfortunately with the cost of additional type casting to/from int for any non-int/non-bool types.

@gcaria This should prevent the unnecessary type casts to/from int by preserving the wanted/needed dtype from the calculation of the sum. This also works in case of boolean arrays.

There is might be need for a test to catch any unwanted type cast to prevent any regressions. If someone has an idea, please suggest!

thanks @kmuehlbauer !

I've added a code comment and an entry to whats-new.rst. Maybe new tests aren't needed as preservation of float types as well as correct calculation of bool mean is tested. Added "plan to merge" label and will go ahead with that later today if no one beats me to it.