From the US Coast Guard:
Please note the new federal law related to cut off switches effective April 1st.
Who is effected:
Owners of boats less than 26 feet in length that generate more than 115lbs of static thrust (~ 2-3hp) and were built beginning in January 2020. If the boat was built in January 2020 or later, or an ECOS was installed at some point in the boat's life, the Engine Cut-Off Switch systems must be maintained in working condition for the life of the boat.
The Engine Cut-Off Switch Link doesn’t need to be attached when the vessel is idling, performing docking maneuvers or just going slow. The Engine Cut-Off Switch Link must be attached whenever the boat is operating on plane or greater than displacement speed
More details here: