That’s what regen is. All EVs do thatNormally tow limits are due to weight as well. Puny brakes + very heavy cars + heavy trailer?
Apparently Rivian solves this by putting the electric motors in reverse when towing to help slow the car down.
And yes most OEMs haven’t bother with the homologation testing to get a EV to tow bigger weights. They are already heavy cars. Even the Cupra born with a 77kWh had to drop a rear seat to avoid the car being too heavy on initial versions.