It was never cities' job to enforce immigration law either, so legally cities were doing nothing wrong. Rather cities have been working to their own incentives about what best encourages local-law-abiding residents to work with police and get local crimes solved.
Therefore, any so-called "flouting" is pure speech (either pragmatic or political) that we expect to have in an open society. You fascist boosters always dress up Constitutionally-protected activity in emotionally charged language - "flouting", "defiance", "belligerence", "disrespect", and so on - as if we're some dictatorship where obedience is value #1. But this is the exact opposite of the actual United States.
It is however the job of the federal government to conform to the limits outlined in the US Constitution. So if we're talking about the legal situation here, it is the federal government that is in flagrant default, causing chaos and mayhem in American cities. In fact given the willfulness, it's almost like the federal government is being controlled by our adversaries.