Thank you for posting this in Microsoft Q&A.
I understand that when you attempt to enter a mismatched password, it doesn't show an error message until you perform a click-create event.
You can use the special claim type reenterPassword to validate that the user correctly re-entered their password during user input collection.
In order to resolve the behavior, follow the steps mentioned in this document. https://learn.microsoft.com/en-us/azure/active-directory-b2c/custom-policies-series-validate-user-input#step-4---validate-password-and-confirm-password
Hope this helps. Do let us know if you any further queries.
Thanks,
Navya.
If my understanding of the issue is incorrect, feel free to post back.