Sure, but the acquisition was in 2014. I assumed they would want to serve it from their own global infrastructure. Perhaps they have a great deal with Fastly.
They acquired Firebase. On Firebase Hosting for apex domains one needs to add Fastly's Anycast IPs. Switching CDNs would be a nightmare.
One related gripe I have with Firebase Hosting is that it refuses to renew certificates if you also add IPv6 addresses.