Using Pro 3.6 I get this popup every now & then with no obvious source.
I've just opened an existing project and looked at something in the attribute table of a layer. I clicked in the map and this popped up.
I'm not editing or doing anything that could've disturbed an equation, formula, script, or ouija board?

I'm definitely NOT going to apply it seeing as there is no detail about the source but how do you figure out what caused it?
I am used to seeing the message when, for example, you do something to a label class expression and click to the symbol tab before applying the expression but Pro 3.6 seems to flick these on the screen when doing something completely unrelated?