The policy continues: “You can also disable location-based system services by tapping on System Services and turning off each location-based system service.” But apparently there are some system services on this model (and possibly other iPhone 11 models) which request location data and cannot be disabled by users without completely turning off location services, as the arrow icon still appears periodically even after individually disabling all system services that use location.
“We do not see any actual security implications,” an Apple engineer wrote in a response to KrebsOnSecurity. “It is expected behavior that the Location Services icon appears in the status bar when Location Services is enabled. The icon appears for system services that do not have a switch in Settings[emphasis added].

https://krebsonsecurity.com/2019/12/the-iphone-11-pros-location-data-puzzler/

I suspect this is related to its new "find my" mesh

Apple’s use of Location Services data tied to UWB management & federal guidelines
Apple has said that the iPhone 11 family is using location data to regulate Ultra Wideband emissions, but is not collecting the data, and everything is being done on-device.