I know that all* xSeries rfid/nfc implants are filled with epoxy of some kind within the glass. This keeps things from rattling around internally, and provides additional strength to the implant (strength is just a guess, I do not work for DT).
In theory, that epoxy* is capable of preventing or delaying corrosion.
My concerns (again, guessing) from a corrosion standpoint would be copper (antenna) and possibly whatever is in the solder.
If the glass is breached (it has been), it is likely a matter of time before the xNT stops working. Plan accordingly if you use it as a credential for anything (KBR1).
My main concern that is much more time sensitive is actually physical, the glass itself. I speak from experience from here on out. If the cap is broken off, the rest of the glass encapsulation is weaker, and possibly already fractured or cracked. Additional impacts will eventually result in this glass breaking further, both exposing the internals more and becoming glass shards in the hand.
Take a look at the microscope photos in this post, and possibly read through the post for more info. Note: I do not recommend self removal.
The cap is likely to be a non-issue on its own, and removal could potentially be more damaging than what damage it could do. This is a mostly dull, clean piece. The rest of the implant should be removed asap. I would reach out to a medical professional if you can. A trusted installer may help too.