If I enable the location (via GPS only) I always get a location icon in the top bar and it always seems to use my location, which if of course worrying for privacy reasons.
However, I’ve noticed what is causing this issue: A preinstalled app called “Service menu”.
That is apparently started on each device start. To see it when you view the last location request, the usual location screen you get does not help (Settings -> Location -> Show all). You also need to go to the three-dots menu there -> “Show system apps”.
You’ll see “Service menu” in that list.
Fortunately, you can go there and stop the invasive app. But what does it actually do?
What is it used for?
One can also see it stores plenty of stuff (35MB is a lot, actually) and may have used some network data? The problem is if you tap on “Mobile data and WiFi” there, you get a screen of “Android system”, so it accumulates all usage, which is not useful at all.
Here it is shown after I’ve stopped it: