Oculus does staged rollouts of updates. Nobody is getting V28 on their headset til tomorrow at the soonest, and for many it’ll be days or even a week or two before they get it.
In addition to that, they also activate new features in stages, so even if you had v28 firmware, you still probably wouldn’t have the new AirLink or other features for a while.
One last general note – the PC app and headset firmware are two different things. Both of them have the same version number, but to use new features like AirLink you need both the headset firmware and PC software updated.