I can even reproduce with this page:
<!doctype html>
<html>
<head><title>foo</title></head>
<body>
<a href="https://forum.our.tld/t/title/3940/551">https://forum.our.tld/t/title/3940/551</a>
</body>
</html>
When clicking on the link I’m in the redirect loop, if I copy/paste it it works.
I’m … puzzeled.
The only thing I can think of that’s different in a browser when clicking on a link vs. copy/pasting the link is the referrer.