Some Brushes change from "Brush tool" to "Smudge" Tool.
Using PS 21.2.3.
Even though my Brush Tool is selected, it switches to the Smudge Tool when I select the Wet Media - Kyle's Paintbrush Wet Blender or Kyle's Impressionist Blender No.1. Once the tool switches to Smudge, the only way to return to Brush Tool is to select another brush.
I'm not going to waste time by finding out how many other brushes act this way.

