Most other AX models (AX42, AX52 and AX102) also have serious reliability issues, where they will fail after some months. They are based on a faulty motherboard. Hetzner has to replace most, if not all, motherboards for servers built before a certain date over the next 12 months [0]
I have two AX42's. One has been stable since I got it during the Eurocup discount period. The other got replaced 2 times so far, but it looks like the latest replacement is holding up. So, it's like 50% failure rate based on my small sample. I guess only Hetzner and ASRock know the real numbers.
[0] https://docs.hetzner.com/robot/dedicated-server/general-info...