“For the case of this post, I will define IP address squatting as “using IP addresses that are not RFC1918 defined and not your unicast space issued by a RIR”.”
Networks run out of private space and quietly grab public blocks they don’t own, often the Pentagon’s unannounced ones. It works right up until the owner turns them on. Cloudflare found that out when 1.1.1.1 collided with every router squatting on it. IPv6 fixed this two decades ago, and almost nobody moved.