The Rufus FAQ page addresses this error:
From: https://github.com/pbatard/rufus/wiki/FAQ
<excerpt>
This error comes from Microsoft, since Rufus downloads Windows ISOsdirectlyfrom the Microsoft servers.
In early 2023, Microsoft have stepped up the anti-abuse protection of their ISO download servers and are a lot more proactive (read: aggressive) at banning IP addresses that they consider to be either putting excessive stress on their servers, or that come from a specific region that they want to filter out.
</excerpt>
As a workaround, please download the ISO using the Windows 11 Media Creation Tool.
Windows 11 Media Creation Tool - Download link:
https://go.microsoft.com/fwlink/?linkid=2156295
How to Download Windows 11 ISO Using Media Creation Tool: https://www.winhelponline.com/blog/how-to-download-windows-11-iso/