IP Block Owner are sites where the Origin AS name is similar to the domain name in question. Meaning the business probably owns one or more IPv4 net blocks.

The minimum size netblock is generally /24 which provides 254 IP addresses and as of September 2022 costs around $51 USD an address so a minimum price just under $13,000 USD. A /18 netblock with 16,384 IP addresses can cost up to $1,000,000 USD.

A working example is enterprise.ca. It has an IP address of 148.78.93.26 which is a /24 block with an owner name of "Enterprise Holdings, Inc" - the website enterprise.ca would contain the IP Block Owner technology tag. Most websites will not have an IP Block Owner but will show the hosting company that owns the block instead.