Google
As a curiosity test, I logged in (so I could post) then typed "www.google.com" for a hyperlink. Then I logged out and noticed the forum software evidently did a DNS lookup... it displayed "Google" as link text.
While logged out, clicking on the link text displayed the dialog 16ACE27 referenced above. So, I think that works as designed. But notice in the text I pasted in there are no characters outside the "standard" ASCII set.
Then when I logged back in and viewed the post, the software had automagically formatted my typed text into a proper url - likely using the data from a DNS lookup - and even enclosed it in tags/brackets.
Notice when logged out the link is prefixed for redirecting to the "External Links Notice"... AND the non alphanumeric characters are NOT ASCII encoded.
So... I 100% agree with 16ACE27... the forum is possibly using an outdated encoding algorithm, and unless the forum upgrades to an updated version...
Finally - apologies to oldWEB if I offended you. That was NOT my intention... I actually want to applaud you for sleuthing out those broken links. Cheers!