AWS developed two generations of an in-house ARM chip (Graviton), which I think is cheaper for an equivalent power to an x86 instance. Cloudflare has also begun switching to ARM, for 57% more performance per watt:

https://blog.cloudflare.com/designing-edge-servers-with-arm-...

The cloud providers have been buying Intel for years and can't afford to just throw thos chips away. AMD is capturing a much larger proportion of data center CPU sales, but you should still expect to see them buying Intel as well, since AMD can't produce enough chips to satisfy all demand. Also, qualifying new platforms is very expensive so cloud providers will continue to buy already-qualified platforms for as long as the perf/W makes sense.

The past 2 companies I've been at have or had huge efforts to migrate large parts of infrastructure to AWS Graviton which are 64-bit ARM iirc.

AWS certainly offer AMD boxes as well (M5a, M6a, T3a etc), but nothing like the broad range of Intels, and not even the same kind of offerings as Graviton.

ARM is increasingly being a factor there afaik.