Spot on, it is definitely a Repair insert, that has backed out with the plug when you removed it.
I would NOT do any "re-inserting", unless you are educated and well-practiced at Time-Sert Spark plug thread repair, in which case you wouldn't have created this thread..
There is a kit worth of tooling needed to install these properly, including a cutting tool to cut a new Spot-face for the crush washer to seal against.
Furtherly, there are Insert Install/Removal tools for properly installing them, so this does not happen again next Plug change.
I just went through this on my Y7 last week, ended up pulling the head and taking it to the Machine shop that performed the repair 1st time around.
They fixed it free of charge (as they should have).
They did inform me, pulling the head was not necessary for the repair, but it made more logistic sense for me to leave them the head rather than the entire car.
I'll make one exception: You could try threading that same Plug/Insert combo, right back in (make sure you know which cylinder, for obvious reasons).
Snug it by hand, Torque to 156 In./lbs., and see if it holds (Tq. value came straight from my FSM).
It likely will, but alas, you are stuck with a 'used' plug, until it is fixed correctly.