It's a joke, but the fact is that the diagnose button only searches event logs and windows system logs for errors against only a small dictionary of problems.

This is exactly why Microsoft has been playing with a locally installed nano AI driven fix it utility for future updates: the current one sucks.

edit link:

https://windowsforum.com/threads/revolutionizing-windows-troubleshooting-with-ai-powered-fix-it-button-in-windows-11.365216/