I agree that it's not common to get squibs in .22LR that result in a bullet lodged in the bore.
In centerfire rounds, squibs are caused when the primer ignites and the powder charge doesn't ignite or only partially ignites. The force of the primer and/or partial powder ignition drives the bullet into the bore but is insufficient to get it out the muzzle.
In rimfire rounds like .22LR, the most common failure mode is that there's a problem with the primer and the round doesn't fire at all. Relatively speaking, you don't hear about squibs lodging .22LR rounds in the bore that often.
You can make this much less probable by purchasing good quality ammunition and storing it properly. In addition, you should always unload the gun and check the bore (regardless of the type of firearm) if you fire it and the noise of the report and/or the amount recoil seems unusual.