BUG: isin fails to correctly compare None values.
- [x] closes #35565 
- [ ] tests added / passed
- [ ] 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

@DriesSchaumont can you respond to jreback comments Hi @jbrockmendel, I am in the middle of moving to a new place and I currently have limited internet access. I will try to come back to this PR as soon as possible. I hope this is not blocking anything?   > I hope this is not blocking anything?

no, not to worry Seems I accidentally pushed a commit that was meant to be in another branch. Updating this PR now. I will add a comment when this is ready for review. if possible we should reuse libmissing.is_matching_na closing as stale, if you want to continue working, please ping.