Weird comment bug trowing 404 error

Hi all,
I have the weirdest bug I ever saw and it’s on my blog… The post gets 32 comments, but the 33rd is trowing a 404 error. The guy was kind enough to email me the comment and I tried posting it with the same result. I played around and finally I realized that it seems to be cause by something in the comment body. I checked on https://string.online-toolz.com/tools/string-functions.php but it doesn’t show any hidden character.

This is the string, by the way: “strap on my Panerai.”

What can cause this error?

Thanks a lot for any advise!