I had an adult sim who's face would turn elder when she was wearing her business uniform.
I had a whole business that did that. Their faces turned to elder faces whenever they put on their uniform. They maintained their adult posture, just had old faces. The mirror didn't help in their case.
Weird part was it happened no matter what outfit I chose as a uniform. It didn't matter whether the outfit was a uniform, regular clothes, Maxis meshes, or custom. I could put a bikini on them and as long as it was being called their "uniform", their faces would be elder. I never did get it fixed.