Been using a dexcom g7 for a few weeks as a test. Pulling the sensor off can be painful, and leaves behind adhesive residue when I do it. And there's also a bit of inflammation in the area since it sticks a small probe into you, which sits there for 10 days.
I mean the probe itself, which appears to be wire encased in plastic. When I said "left behind" I just meant that the probe is placed below the skin as intended, not that anything remains after the sensor is removed. This is the part that would be considered "invasive."