There is another possibility. Don't know if it applies to you of course, that's up to you.

There may be a water leak into the cabin. Check the floor and carpets carefully on the passengers side. Several times I have found wet or soaked carpet there when I have trouble with very slow defogging.

There is a drain in the fresh air intake plenum that can get plugged. This has happened several times to me. The plenum drain is found under the cowling. So you (or service folks) must remove both wiper arms/blades and cowl/grate to expose the drain which on the far right (passenger) side.

There is a grate in the cowl which is meant to keep leaves and such out of the fresh air intake plenum but bits and twigs can still get through and plug that drain. Once plugged water will spill over and make it's way into the cabin near the passengers feet.