@tefra, now that issue42904 has been solved, can you test your code again with 3.10.0a8? (it's not out yet, so you may have to pull the code from CPython's GitHub master branch and build CPython)

Running your code again, it seems to be fixed:

Python 3.10.0a7+
>>> from typing import get_type_hints, Optional
>>> from a import Root as RootA, Person as PersonA
>>> from b import Root as RootB, Person as PersonB
>>> roota_hints = get_type_hints(RootA)
>>> rootb_hints = get_type_hints(RootB)
>>> print(roota_hints)
{'a': typing.List[a.Person]}
>>> print(rootb_hints)
{'b': typing.List[b.Person]}

However, it's still around for 3.9 and below if I use string annotations in classes. There's some discussion in that issue about why it may not be backported though.