This is the current error page:
Error!
There was an error on the server. Try refreshing your browser. If that doesn’t work, come back at a later time. If the problem persists, you can seek help in the Lemmy support community or Lemmy Matrix room.
The links both point to the same place so that should probably be fixed. I think it would be a good idea to add some more Lemmy.world specific info there like https://lemmy-world.statuspage.io/ instead of just a general Lemmy message. Other options could be a Lemmy.world mastodon news feed or a backup support community on another Lemmy instance.
Unfortunately it doesn’t look like there is a way to customize this message right now (without building Lemmy altered from source that is).
Relevant code: https://github.com/LemmyNet/lemmy-ui/blob/main/src/shared/components/app/error-page.tsx
Relevant translation file: https://github.com/LemmyNet/lemmy-translations/blob/main/translations/en.json (line 235 and 236 at time of writing).
Found a related issue, as suggested there a workaround with a web server config (or maybe cloudflare) could be possible.