In a situation where this is just a 1st mortgage only - the mortgage is secured against the property.

If there is a 2nd mortgage - I have seen multiple times where a 2nd lien holder goes to court, gets a judgement, and garnishes a checking account.

Banks don't have that kind of power. If you live in a judicial state they have to get a court judgment to collect funds. If you live in a trustee deed state and you have an unprotected second then those often go to collections.

Freezing your access to your property or funds in an account is equivalent to interfering with your ownership there of....and that takes a judge to do that, the bank can't unilaterally do that.