Common issue seen when others have bad internet connection
Yeah, this can happen for a couple of reasons.
First: in order to save resources, there a gaps in the updating of other users’ actions. Every so often the aircraft you’re seeing updates what it’s doing to align with the actions of the user piloting it. In between these updates, the aircraft just continues the last updated action, even if that isn’t what’s really happening. The amount of time between these updates is dependent on how far you are from the pilot. The further away, the more time between updates. You can see this if you pay attention, especially if the pilot is making lots of inputs. The plane will seem to jerk around and make sudden changes instead of smooth rolls and pitches.
The second: like @flopperben said above, sometimes there can be connection issues, and these issues play out very similarly to the situation I explained above. The aircraft that you see just keeps doing what its last known inputs were, even though the actual craft landed properly. Because there are no collisions between the models that we see and the ground, the aircraft just continued to descend and eventually sunk into the ground.
So, don’t worry, there’s nothing wrong with this, unless you want to blame other people’s internet connection, or the devs for wanting to save resources so we could have things like better shadows!