BUG: inconsistency in dtype of replace() #44864
- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit) for how to run them
- [ ] whatsnew entry

you already have https://github.com/pandas-dev/pandas/pull/44869 pls don't open multiple PRs for the same issue. you can push to the original.