Those are IPv6 addresses that work a bit differently than IPv4. Most customers only get assigned a single IPv4 address, and even a lot of big data centers only have one or two blocks of 256 addresses. The smallest allocation of IPv6 for a single residential customer is typically a contiguous block of the 18,446,744,073,709,551,616 addresses mentioned.

If Google’s security team is even marginally competent, they will recognize those contiguous blocks and treat them as they would a single IPv4 address. Every address in that block has the same prefix, and it’s actually easier to track on those prefixes than on the entire address.