Your phone will locate and report bluetooth ibeacons, and allow apple to update their crowdsourced location databases.
The same thing with wifi (which has the same behavior in control panel)
It would have been SO SIMPLE to have a nicer pattern. short press to disconnect, long press to turn off.
Indeed, this is exactly what I expected would happen when I long pressed and I was disappointed when it didn’t. There are definitely times like this when Apple’s UX gets more credit than it deserves.
Which is one of the reasons why I'd always leave Bluetooth/WiFi off by default, and only turned them on when I actually need them: Cut way down on the battery draw.
That option is now gone, instead the default has become "everything is always on", drawing on the battery, thus forcing you to recharge more often, cutting down on the lifespan of your battery.
Not saying that was Apple's plan all along, but it's one of the outcomes of this pointless change. When the solution to this could be as simple as "double-tapping the icon will turn it off permanently, tapping once temporary".
....No, it's really not.
You can still turn WiFi and Bluetooth off (really off) from the Settings app, and they will stay off until you turn them back on.
You can even turn them back on from Control Center.
It's fixing the annoying issue of today's AirPods failing because of something I did yesterday afternoon which I forgot.