

Playing information ping pong. We sent them some issue with a lot of information and instead of actually investigating they often dragged on the whole thing by asking for details they should have themselves, taking hours-days to respond etc before they actually did something. We often had to escalate issues via our account manager.
This was all on enterprise support while I was working for a company that paid six figures each month for infrastructure in their data center.
I think the only thing where you can mix CPU architectures without much problems and doing something meaningful with would be a Kubernetes Cluster, e.g. install K3S across the machines.
As others mentioned, the 3rd gen CPUs are probably using quite a lot of power. I’d get something to measure how much the whole machines draw from the wall and decide if you’re fine with that (measure while there’s actually something going over the network interface and some r/w operations).
The CPUs should be powerful enough to run most classic selfhosted apps.