It still happens after scaling it bigger. Also, it was the same size as the tutorial version, so not especially small. I tried turning on/off the GPU Depth Picking in the viewport preferences. Didn’t help.
There is a thread here that seems to describe the same issue - Blender is selecting vertices from behind WITHOUT XRAY
It doesn’t does happen in the project that you uploaded. I will start a new project and try again to see what happens.
EDIT - I started a new project and this issue only seems to happen after adding the Solidify modifier.
I also found this link where someone had the same issue, but I don’t really understand the reply they got - https://blender.community/c/rightclickselect/08Kv/?sorting=hot
I am selecting vertices using the box select, but I also tried it with the paint tool (or whatever that is called when you press C).
Here is my most recent attempt -
Blender Guru Donut 001.blend (944.3 KB)