What is causing the allegations of a quid pro quo between Mayor Eric Adams and the Trump administration?

The allegations stem from the Justice Department's decision to dismiss corruption charges against Mayor Adams after he agreed to cooperate with the Trump administration on immigration enforcement. This sequence of events has raised concerns about a potential quid pro quo arrangement between the Democratic mayor and the Republican administration. The situation has become so serious that it's triggering discussions about the rarely-used process in New York City's charter where the governor can remove a mayor—a provision that has never been implemented before.