Why did my Apple Pay on my phone lock

Hi there,

Please see this

Your account may be locked if there's suspected fraud on the account, or if additional security checks need to be completed. If your account is locked, you can't use Apple Cash to make purchases, send or receive money, add money to your account, or transfer money to your bank.

If your account is locked and there are no instructions provided, contact Apple Support.

See this link for further reference

If Apple Cash is restricted or locked - Apple Support