Often in my designs, I’ll use an “advanced” font settings that just don’t show up in Dev Mode. Small caps and monospaced digits are the big two culprits. They would either have to know that something looks different, go into design mode, and look at the typography settings themselves, or I would have to remember to call it out.

Here’s a label I have that uses SF Pro’s monospaced digits; there is nothing that hints at this feature being enabled: