Just when Ampere are exploring a sell. So realistically no one is actually competing in the ARM server CPU market other than HyperScaler making their own chip. Nvidia for whatever reason doesn't seem to want to enter the General Server CPU market either. So this is pretty much ARM doing it themselves.
Related Arm secures Meta as first customer for ambitious new chip project (14 points) https://news.ycombinator.com/item?id=43039901