I think often it’s hard for people to accept Designers come in shades (just like every other profession) so it’s easier for them to imply all designers are visual or all designers should do user experience or whatever set of skills.

I think the best way to deal with them is to not let know reduce the profession. So instead of saying, “design isn’t visual aesthetics,” leaning into, “yes, that designer is very good at aesthetics,” may very well be the better option.

Lift your colleague up, affirm that person for pointing out one aspect of design, and then it gives you leeway to also say, “other designers have other specialities,” or, “I’m working on expanding my skill set in this direction to complement them.”

Maybe you’re working in a corporate setting and that sounds reductionist to you, but to me it means you put care into your work and your individuality is showing.

Personally, I think it’s a compliment to be called an artist or a craftsman.

In summary:
Telling people Design is not just aesthetics doesn’t seem to really do much except make them feel stupid.

You can just agree things are beautiful and it’s fine. That’s how taste is refined over time.

Amateur designers get into the industry because they mostly liked how things looked.

Over time you (may) expand beyond visual problems and there shouldn’t be some expectation that someone who isn’t a Designer would somehow know this.

That’s why they hired you, after all.