Yep... same problem here on iPhone 8. It started yesterday and is continuing today.
Like most others; I've restarted phone several times, deleted and reinstalled app, updated iPhone OS (so the problem started in the previous version and has continued AFTER updating to the latest version... therefore it's NOT down to the OS).
After deleting and reinstalling the app it worked, but only briefly before the fault returned.
Again, the same as everyone else it appears to open, then the screen dims and the app disappears/fails to actually open on-screen. However, it is clearly 'open' as when double clicking the home button to show all open apps the Airbnb app is visible as running, yet when you touch it to bring it to the fore, it again dims the screen momentarily and fails to 'open on screen'.
works fine on iPad, but that's of limited use to me when out and about.
Please Airbnb get this sorted urgently as it affects hosts AND guests, very badly!!
Alan