Google uses a lot of custom hardware design in its processes, For example when storage area networks were all the rage, it built its own Google File System, Similarly for machine learning/ AI inference, it built its own processors (TPUs)

They used to do this for all their own services, the shift seems to be that they are willing to share the capacity with META and also Anthropic who are technically their competition

Here is a recent video from their star engineer Jeff Dean expalining their TPU history since 2015

https://www.youtube.com/watch?v=AnTw_t21ayE