Let me preface this by saying I use Discord daily to keep in touch with friends. It's a great digital campfire where you can relax with people, talk with them over voice and video or just post random stuff.
The issue is that Discord has replaced things which it shouldn't have, the internet forums. Discord is the epitome of a golden cage. It is a prison for information, a black hole.
I'm not even talking about the absolutely atrocious search functionality, but the fact that information inside the Discord walls is impossible to find from the outside. You can't search across discord communities, none of the content there is indexed by web search engines. Entire communities have FAQs and knowledge as pins inside threads inside Discord servers. Things which used to be on the web.
15 years ago, these discussions would've taken place on forums and on IRC to a lesser extent. IRC itself was a really bad information black hole, but at least the forums were great. They supported long running discussions and were easy to search.
Now everything disappeared into effectively hidden Discord chats and youtube videos where you need to watch 8 different idiots bramble on for 10 minutes before you find the 30 second segment of information that you were actually looking for and could've been a single paragraph.
Only if it's in the discord search index, which sometimes doesn't include all history, and it does some fuzzy elasticsearch query that works ok for most cases and awful for anything that isn't most cases.
The metadata filters are nice but they're also what keep it usable at all.
Discord search won't even surface partial word matches or typos or matches in URLs (eg you share a facebook.com link then later on you search for "facebook", it won't show you that post).
Maybe there are some secret incantations I don't know about, but Discord search is positively useless most of the time and I have to manually scroll up until I find what I want (or give up).
I still use IRC, irssi in particular. My go-to for searching local logs is `less` rather than grep. I have the date on every line in the log file. I can jump to a specific date easily, then search a different term up/down from that spot, and I see context of surrounding lines easily. No regex needed.
I guess this is like a dunk and I shouldn't even respond, but I'd probably (from less) do /nick.*http and then hit n or N a bunch to jump around. Yeah, it's technically a regex, I guess, but I think it's probably the easiest/most common form. You don't really need to remember much of anything or understand how it works. You could be used to wildcards from a shell and just think "I gotta put a . in front of it sometimes for it to work".
I would not get more advanced than that, personally. Sure you'll have matches that aren't exactly what you're looking for, like that'd match both lines I said and lines mentioning me, and URLs that aren't images (better than trying to account for all types of image URLs, IMO) but I'll probably find what I'm looking for fast enough for it to not be worth looking up more complicated regex. Often I'll remember who posted something, too, so then maybe I'll throw their nick in the search as well, before mine. Or at least I could narrow down who posted it to a few people and just try a few searches pretty quickly back to back.
I would also say this particular search you're talking about would be fairly uncommon. I might even remember something like "oh, Bernie said that image was the funniest thing he'd seen all day, I'll search the word 'funniest' starting from the end of the file since it was under a month ago and should end up near the URL".
You would then also need to search for /http.*nick, as he might mention you after the link.
IRC had so much potential, but somehow we fumbled it. A simple search based on local logs and for the user hidden reg-ex could have been implemented 10+ years ago.
Discord search still sucks a lot because by nature discussions are largely unstructured. It's not really suitable for discussing specific topics - only perhaps types of topics. Discord threads could ostensibly fulfil the forum topic role, but their implementations is so utterly incompetent that it is genuinely puzzling. You can't search specific Discord threads, they often disappear from the left hand nav bar even if you subscribed to the thread. Whoever implemented the Threads in Discord should be kept away from computer systems because they are a danger to any application.
But even if Discord search was good, it still doesn't matter because it is not only a walled garden, it is a hermetically sealed chamber from which no information can escape.
The issue is that Discord has replaced things which it shouldn't have, the internet forums. Discord is the epitome of a golden cage. It is a prison for information, a black hole.
I'm not even talking about the absolutely atrocious search functionality, but the fact that information inside the Discord walls is impossible to find from the outside. You can't search across discord communities, none of the content there is indexed by web search engines. Entire communities have FAQs and knowledge as pins inside threads inside Discord servers. Things which used to be on the web.
15 years ago, these discussions would've taken place on forums and on IRC to a lesser extent. IRC itself was a really bad information black hole, but at least the forums were great. They supported long running discussions and were easy to search.
Now everything disappeared into effectively hidden Discord chats and youtube videos where you need to watch 8 different idiots bramble on for 10 minutes before you find the 30 second segment of information that you were actually looking for and could've been a single paragraph.