The concept of putting Arm chips into servers was dreamed up in the bad old days when Intel was the only game in town regarding performance, and as such they could - and did - charge whatever they wanted. Hence an explosion of companies trying to make Arm for server a thing.
About the same time those companies launched their first-generation products - which were entirely unimpressive - AMD dropped Zen, and the prospect of Arm servers immediately died. Because Zen brought x86 prices back down to the point where the pain of adapting your entire company's software to Arm was no longer worth it. Fortunately for the Arm server companies, they had investors who hadn't yet realised they no longer had a feasible product.
Unfortunately for the Arm server companies, those investors have now woken up and are demanding returns. Unfortunately for those investors, the only way they're going to make a profit is if their chosen Arm server horse gets bought by a company big enough to need lots of s**tty, slow CPUs. The only companies that fit that bill are ones with thousands of s**ty slow VMs, aka the big cloud providers, and Amazon already bought an Arm server company, which leaves only Microsoft or Oracle - neither of which are likely to bet on non-x86 tech.
I'm expecting Amazon to dump their purchase in a year or so, and the other Arm server companies to follow shortly after. The value proposition simply isn't there.