Unauthorized Bluetooth Connections

Hi,

I recently moved to a new apartment and noticed there are unknown and unauthorized electronic devices connecting to my iPhone AND MacBook, "Galaxy S10+" or "Nexus". When I go to the bluetooth settings on my phone, usually to unpair it there is an i with a circle around it. However, when I go to unpair it, there is no i. I've been turning the bluetooth off, but whenever I turn it back on, the person can still connect to it. I have never approved it nor has any communication popped up asking to pair. This has been happening to my partner on his phone and laptop as well. Can they access our data? How do we stop these random devices from pairing?