Former web developer, AI/UI dev, and data analyst for various things (including targeted marketing on social media) here.
If you have accounts like Facebook and Google +/Gmail, or any app that requires permissions to read & write your surface settings, then this is why it happens. Your default settings for location and other permissions (mic and camera) are enabled for constant read-write.
What does this mean?
You can toggle your permissions for these apps for conditions like Never or While Using App. Keep in mind that if you have apps opened up in the background of your phone, then you're technically using them. Make sure to close them out completely when you don't want to use them.
But why?
When you have your location permissions enabled for apps, this data is collected and used for targeted marketing. Google is the biggest offender.
Example of how to stop active data collection
You can pause permissions on Google accounts:
You can toggle app settings for surface permissions off:
Friendly Reminder
The more you create accounts by using your Google or Facebook to login, the more active data collection you offer to these companies. Unfortunately, Facebook will never not offer you the chance to not have ads showing on your newsfeed. However, you can shut off channels of active data collection by signing up with an email address and a good ol' password instead of using SSO (single sign on) with Google or Facebook.