Anyone else having trouble with the Preview feature?

[TerrorDæmonum]

The problem appears to be related to some configuration of the forum or the host.

It is also new. See this post: https://www.suscipedomine.com/forum/index.php?topic=26152.msg544097#msg544097

The link it in is nothing special, but it contains the single string that causes this to happen. Quote the post that contains that link and try to preview  or quote and post it the response with that link in it and this problem can be replicated.

The trigger is actually just the subdomain and domain, not the rest of the link.

[TerrorDæmonum]

Perhaps we will soon find out whether the problem can be unraveled or whether I am truly being cyber-attacked.

It is not you or any of us. It is the forum and the host, and ultimately, Kaesekopf.

The problem is actually a very specific string:

.us.archive.orḡ

The filter is targeted towards this when it is an org, rather than an orḡ. Changing any single character will be fine. It is not case sensitive.

Feel free to email me the link, Miriam, and I can poke around...

It sounds like you did poke around. I thought it was either the user or the string, but in the end, it turned out to be you. That was fun this time, but please don't do that again. Finding the regex that is blocked is not so fun. Fortunately, it seems to be a literal.