What exactly are you doing, just clicking The Guardian link
https://www.theguardian.com/international
and what it hangs just trying to render it down?
Im in Au so it's redirecting to
https://www.theguardian.com/au
I've Installed STP Release 130 (Safari 15.0, WebKit 17612.1.26.1.5) this morning, so now, I clicked your link, it doesn't misbehave.
I've clicked quite a few articles on the main page, it loads very fast, not hanging as you describe.
I have DarkReader extension and Ad Guard extensions typically enabled and i've disabled these to test again, and no, no issues in page download it's even fast with all these spammed adverts, gosh that's atrocious, how people browse like that ahaha
Must be something else going on,
right click in the main window select Inspect Element in free space form the contextual menu and select the Network tab in the Inspector, reload (Command+Option+R = no cache reload)the page and see what resources are getting hung on, it could actually be some assets on 3rd party CDN that't not able to connect to from your route.