This article is about the “AI chips” Nvidia makes that undergird the major cloud services though, not the cloud services themselves. So I think it’s a hardware issue, more akin to a monopoly of GPU or CPU markets? Especially since Nvidia’s competitors in most spaces seem to be limited to AMD and sometimes Intel.
I can certainly imagine Nvidia having anticompetitive practices with their hardware and/or the software for their hardware, as they have done so many times with GPUs, though this particular article really doesn’t go into any detail.