> The dots always represent the three levels of heat, just like on your iron.
Just to highlight how non-universal these symbol are, I have never had an iron that has three levels of heat or that represents the levels with dots.
It's not "only three levels". All my irons have had "continuous" "level" knob, with three "presets", represented as dots. Along with other "presets" for different kinds of things to iron. But maybe that's Euro thing.
Funny thing, those two do not match. For example, on my current iron "Cotton" is marked at three-dots, whereas all my cotton clothes have labels that insist on ironing them on two-dots.
I remember this in spite of not having done laundry in 5 years. And you're exactly right. New symbols mean little to me, I would still need to look them up and then there would be twice as many bad symbols.
This redesign article is an example of why you should avoid UI/UX people who can only design. They'll change your branding everytime they get bored and create more headache than they solve.