[gwern]

Yes, without the swapping JS, you wouldn't get the canonical URL. But browsing Gwern.net these days without JS is pretty painful. And in this particular case, there is only one place on Gwern.net that the link exists where you could see it without JS; in the other 5 or 6 links, you could only get there via JS and thus the swapping should've happened. So it is not a safe assumption that OP simply browsed with NoScript.

[sleepingreset]

Hi Gwern, I'm honestly not sure. I have some firefox extension that skips trackers and other redirects. I have like 100 firefox extensions, actually. I'm not sure how most of them work nor what they do exactly, I just trust that they make my browser more "secure" and I tend to download things at random -- especially if I see ads or want certain features in my client (i.e. a browser that auto-rejects cookies).

Happy to try and help you figure this out but when I revisit this specific hyperlink I'm still getting the gwern url & not arxiv

[gwern]

Hm. So you're getting the raw URL but you don't have NoScript / block JS specifically? Can you check in an incognito window and if it still happens, ablate all your extensions in a fresh profile (https://support.mozilla.org/en-US/kb/profile-manager-create-...), which is something you might want to keep handy if you really have 100 extensions running and no idea what they all do...