Agg functions for df not respecting numeric only with level
- [x] closes #40660
- [x] tests added / passed
- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [x] whatsnew entry

stumbled accross this one
thanks @phofl 