In his latest series for Blender 5.0, he teaches you how to make this mug.
But at some point in the video, he attempts to make the bottom of the mug, but fails to first apply the solidify modifier before using the extrude tool, which causes an indent to form on the inside at the bottom of the mug (pic related)
When he notices it, he quickly pans away the camera, and doesn't even address the problem, even though everyone who follows the video will end up with the same result.
This dude has been using blender for 22 years, but can't even model a mug.