Soap suds coming from the overflow vent on the bathtub but the tub is draining properly. What do I need to do to solve this problem

If all plumbing fixtures drain OK, then that could mean that you are using detergent with lots of suds. Washer and tub drain are connected in one, common drain so suds have way to back up into the tub. They make laundry detergents that do not produce lots of suds. Try that one. See if that helps

Hope that explains

Milo