If you’re using powdered detergent, make sure yours doesn’t have zeolite as the water softening agent. It will deposit in the machine, and starts eventually covering the fabrics with a talcum-like powdery substance. It gets especially bad if you either have to use a lot of detergent because of hard water, or are overusing the detergent.

Zeolite was brought in to replace phosphates due to environmental concerns, but it has its own problems with the washing results.

One other thing that often ruins the freshness of clothes for me is overly scented/perfumed detergent. The smell can get quite overwhelming, and contribute to a chemical-y smell and feel.