Water Damage under Passenger Window

[Psneeld]

I had the exact same look/issue.

From that picture, looks like the water is highest right around the hole where the yellow/white wires come through.

On my coach that was the power wires for the exterior mirror. I panicked and thought my window was leaking but dreaded that repair. Got to thinking and pulled the mirror off and found a badly seated gasket that had a leak on top and also plugged the drain on the bottom.

Reseated the gasket, added a bit of butyl tape and leak stopped. Took about 1/2 hour instead of unsealing a perfectly leak free window.

I see you did take the window out...but if that is the hole/wires going to a mirror, might want to check that too before declaring victory. The rubber gaskets on some mirrors are very narrow and easy to fold over/miss their place on the mirror.