Rep. LaMonica McIver (D-NJ) charged for violating Title 18, United States Code, Section 111(a)(1) for assaulting, impeding, and interfering with law enforcement.

But they dropped the charges against the mayor who was trespassing?

There seems to be little doubt that the congresswomen in question shoved and possibly threw punches at least one ICE agent. If we use the same logic and legal principles we used for the January 6th defendants, then they have her dead to rights. She quite literally broke not just the letter of the law, but she did so with every intention of breaking the law. There is not a Democrat in congress who is not aware of this law or openly applauded the use of it on January defendants. So what exactly is her excuse going to be?

ICE facilities open to politicians for cursory visits. If they want to see specific inmates, then they need to provide the names of who they want to see and make an appointment. Now we are not sure exactly what prompted the situation (likely had to do with the mayor who is not entitled to visit with the congress critters). But either way, things got heated and they were asked to leave. At some point, your right to visit ends and you are required to leave. Nowhere in your list of rights do you get to engage in any sort of fighting with law enforcement. If you do... well, you broke the law. Whether or not you get charged is a matter of discretion. Ten years ago? Nobody would have considered a charge. But January 6th and the lawfare against Trump changed everything.