If the phone falls onto a surface it has the chance of the sPen ejecting itself from it's silo @muzza
The sPen on my Note 9, Note 10 and Note 20 all do this.
However it shouldn't just drop out without any actual force.
Daily Driver > Samsung Galaxy s²² Ultra 256Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help. " This is the way. "