In Beta 7 of iOS 12 and macOS Mojave, Apple removed a major new feature.
Recently, with the seventh beta of iOS 12 and macOS (10.14) Mojave, Apple removed a major feature it talked about at WWDC18 – Group FaceTime. They didn't give any reason to why it was removed - only saying it would be back "in a future release of iOS 12 and macOS 10.14".
We can't really complain, because something removed, and added back later with full functionality is better than a half-broken, finished feature. It's good to see Apple perfecting its features - iOS 11 last year wasn't perfect at all.
Although no reason was mentioned as to why Group FaceTime was removed, it's most likely to do with call drop-outs, bad call quality, and user interface glitches that some users reported. We will see this back in iOS 12.1 or above.
Apple likes to perfect it's products and features - last year the HomePod was delayed, so was AirPlay 2, Apple Pay for iMessage and other things. This goes back all the way to the 90's, when they delayed new Macs due to problems.