I find Discord's search functionality to be severely limited compared to that of other platforms (for example, Slack). It's slow, the search results are relegated to a tiny sidebar, date filters are clunky, you can't search across all DMs at once, and perhaps worst of all, it's severely rate limited: After clicking through somewhere around 25 pages, it will fail and also force you to re-send the search query, and then navigate back to whatever page you were on.