Over the last few weeks our washer has begun to stink unbearably.
We have always left the door open. I have cleaned out the tray, done the bleach and vinegar cycles. Switched to powdered detergent. Cleaned and scrubbed the gasket around the opening. Everything. I did a load of wash and the clothes reeked something awful. I could smell it coming up the stairs.
It is getting worse with everything I do.

Our old one had a filter that needed to be cleaned behind a very visible access panel.
This Whirlpool has a complete front face with no place that I can find a place for a filter and googling is coming up with nothing.

Sounds like your drain is backing up into the washer.

Our front loader has a filter behind the kick panel down low