If you pick Eyedropper tool and hold it to sample a color continuously — it blinks, jumps, tries to change into a default pointer arrow.
Take a look at the small GIF attached, or watch a video by Laura Coyle here: https://www.linkedin.com/posts/lauracoylecreative_adobeillustrator-color-activity-7274877800715583491-HkxB

Happens on both Windows and Mac.
And so you know it can work better and some other succeed — compare it with the way Affinity Designer does it (the second GIF).