Use cleaning cycle with a cup of bleach every few months.

Consider using bleach in your white load whenever you do laundry

As said above, I always leave the washer door ajar (amz has a nifty gadget called a laundry lasso that helps with this). I also pull out the detergent drawer, dump out any water, and leave this ajar also.

I leave both the washer door and detergent door open. I also clean with vinegar the bottom part of the gasket. Strangely this problem has started at the top/hard-to-see part of the gasket.

I will try the bleach option.

That’s very bad. I suggest running the Tub Clean cycle with bleach as mentioned above, but also taking it one step further and running a Sanitize cycle on Heavy soil with a dishwasher tab first if possible.

Also, use less cold water washes.

Cold and warm water washes are what cause this. Have had front loaders for more than 20 years and never any mold. Most washes are 140F with only a few at 105F and almost all higher.

I've never had any mold or odor problems in the 20 years I've had front loaders. I only use warm, hot, allergiene, and sanitize temperature levels. No cold water washes here. Leave the door ajar as well as the detergent dispenser drawer pulled out a little bit to air out.