I use Matomo 4.0.0-b3.

When I click on the Performance report icon, then on "online guide" in the bottom note "Note: Some of those metrics might not always be available. You can find more information in our online guide.",
I get a 404.

Besides this small broken link issue, I'm very curious to know in which case(s) these metrics aren't available. We've upgraded this morning to 4.0.0 for that feature and these metrics aren't still available (blank) :(