I believe the premise is that airplane mode disconnects the OS from the modem, but it doesn't necessarily turn the modem itself off. It's still hitting cell towers and phoning back to Qualcomm. If Qualcomm has this information, three letter agencies have this information.
https://old.reddit.com/r/LineageOS/comments/gdu8l4/aeroplane...
I believe the premise is that airplane mode disconnects the OS from the modem, but it doesn't necessarily turn the modem itself off. It's still hitting cell towers and phoning back to Qualcomm. If Qualcomm has this information, three letter agencies have this information.