As others have mentioned- if you have audited your own project for PropTypes uses but you’re still seeing the warning- it’s likely coming from an upstream dependency. One way you can track down the cause of this warning is by setting a debug breakpoint where it’s logged and then stepping back to the caller. Here’s a quick example recording I made:
(A higher-quality version is available here.)
Once you’ve identified the library in question, consider filing a Github issue (or better yet- a PR!) to inform the authors of the new warning.
In the meanwhile, this is only a dev-mode warning so it should not affect production usage of your application.