Thank you for posting your query on Microsoft Q&A. From above description I could understand that you are looking for custom banned password in password reset user flow.
However we don't have these options in user flow. Since Authentication methods > Password protection banned password is not enabled without an Azure AD Subscription.
Rather you could achieve this with custom policies.
Kindly follow A B2C IEF Custom Policy - Sign up and Password reset with banned password list for XML.
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