The old stuff never stopped working, though. You can still use Optional, Union, TypeAlias, and import collection protocols from typing. You don't have to migrate if you don't want to. They're not even deprecated.
I've seen multiple major projects (such a sphinx) break on newer versions of Python due to changes in typing. Typing should make the code more robust, not less.
I encourage you to open the `typing` documentation [0] and search for the word `deprecated`.
Spoiler alert: the search result will be three-figure.
Some of the results are already scheduled for removal.