From a processor architecture perspective, there have been no meaningful changes.I'm not sure how you got the idea that Microsoft's licensing terms haven't changed even a little bit since the 1990s.
The Windows 11 licence is here. There is no mention of different architectures being treated differently. There are no mentions of Intel, AMD or Arm. There is a single mention of "such as" 32- and 64-bit, saying that you may not install both at the same time (and therefore it follows that you can't install the same copy of Windows on both an Intel and Arm machine at the same time; you would need a separate copy for your Arm machine).
If you can find something in there that forbids it, then please point it out and I'll stand corrected.
This quote doesn't seem to mesh with the actual licence text, which is interesting!“Microsoft only licenses Windows 10 on ARM to OEMs,” says a Microsoft spokesperson in a statement to The Verge. We asked Microsoft if it plans to change this policy to allow Windows 10 on ARM-based Macs, and the company says “we have nothing further to share at this time.”