That’s clearly the 20 round magazine for the Ruger 57. A quick Google search makes me think no one makes limiters for that Ruger magazine like they do for the FN five seven the Ruger is trying to compete with.
This dumb troon is openly violating Colorado state law. I think it’s a bad law but as a general rule of thumb, I don’t take pictures of my firearms and post them on the internet for everyone including law enforcement to see.
I don’t think the local town/county police are going to visit them because most likely the local sheriff to bust them on illegal magazines because most likely their more saner residents are in violation. However, these dipshits are going to earn their visit from the state police, especially if their neighbors start making reports about harassment and threats of violence.