Just a note from manually debugging this on our site, checking /logs showed us that our plugin causing this fatal error was Gamification, if you run your forum in safe mode with no plugins (?safe_mode=no_plugins) you should be able to temporarily switch off any offending plugins until you can get a CLI rebuild done. (If Gamification isn’t your only issue, /logs should list the other ones too)
plugins/discourse-ai_admin.js
Looks like one of your fatal ones was Discourse AI.
@hello-smile6’ idea on why this caused a fatal error is from a node version bump.