Other players on the server can destroy someone else's shop
Version 1.18.2
mod version 0.2.2

Because allowing people the create infinite unbreakable blocks is just a bad idea in many different ways, this will not be implemented natively in Numismatic. If you need to have protected shops, I recommend you install one of the many claim/protection mods like FTB Chunks or Get Off My Lawn
Cheers