Some blowback 22s have a hole in the middle of the breech face and on the side of the breech face is a hole for the firing pin What is the purpose of this hole on some striker fired 22s?

Many of the very small auto pistols are made in both 22 rimfire and .25 ACP. They use a common slide that can be used for either. When used for the .25 ACP, it uses a firing pin in the center hole (.25 ACP is center fire cartridge)