Check the operational history section on the b2 page, it’s got a bunch of stuff since 2000.
When again has B2 come in contact with actual air defence?
But again, why would Russia and China be designing/building stealth bombers if they don’t actually work?
Because they both serve a different purpose. Stealth bombers do have a lower profile than regular jets, so theoretically they can get closer to the target. However, the bombs that B2 drops can also be intercepted even if B2 itself isn’t. So, launching hypersonics from a stealth fighter is still obviously advantageous.