This bug only seems to work on Windows.
Illustrator version: 25.2.1

As discussed here: https://community.adobe.com/t5/illustrator/buggy-hidden-invisible-non-existent-appearances/m-p/11964528/thread-id/271978#M272107

Creating a default text object, selecting it, then clicking on it with the eyedropper tool creates an invisible/pseudo-existing appearance on the text. This is evident in that going to the top menu shows that Object > Expand... is greyed out while Object > Expand Appearance is not. You can also see in the Layers panel that the text object has its selection circle filled with grey, indicating that it has an appearance. Yet checking the Appearance panel shows that there is no appearance at all (except whatever is the default).

This apparent bug may or may not be limited to text objects. Although creating a path object and clicking on a default text object with the eyedropper tool shows that the bug occurs since a pseudo-existing appearance will appear on the path object. So something seems to be going on with text objects specifically at least.