What is this hole for in the primer?

Flash Hole Uniformer

A primer on watering hole attacks - Parallel Edge

3M™ High Strength Small Hole Repair Primer Enhanced Spackling - 16

Hole burned in primer. My mistake-wrong primer.

3M SHR-KIT Small Hole Repair Kit: Joint Compound Ready Mixed

Professional Steel Flash Hole Uniformer Selector

3M™ Patch Plus Primer Wall Repair Kit (PPP-Kit)

How to Patch Nail & Screw Holes In Your Walls – Love & Renovations

Too small primer flash hole

3M High Strength Small Hole Repair, Primer Enhanced Spackling

2 X 3M High Strength Small Hole Repair, Primer Enhanced Spackling