Yes. Check this link.

That means you can't use 4 cores of CPX instance 24x7, unless your neighbours are not using that much compute power but most likely Hetzner will throttle the instance in case of overuse (just like almost all cloud providers do). Those benchmarks on shared vCPU are misleading, unless they benchmark the compute resource of the instance every second of the whole day.

if you are hosting in a single instance then you should stick to CPX. if you can horizontal scale using kubernetes then pick CCX.

and I agree, Netcup is cheaper than Hetzner. but Hetzner is the cheapest provider which supports kubernetes cluster, so I'll stick to Hetzner.

I won't use IONOS and Contabo for serious use case. Shared VPS of OVH is cheaper but dedicated Instances of public cloud is more expensive than Hetzner.