You can also just look at your “recent apps” under settings, if a notification popped off in the last 30s and you didn’t see a window then it’ll almost certainly be the top app in “most recent”
It’s a glitch / purposeful design in some apps where the actual popup window isn’t set to actually stick around so it just makes a ghost noise. For me it was some random app I installed for one niche purpose and forgot about
sawdustprophet@midwest.social 5 months ago
I’ve been doing that for years. I only have a handful of apps with audio notifications, basically the most important ones that need my attention right away. Everything else gets vibrate.