iOS 13 has introduced changes to Location and Bluetooth permissions. Estimote has an excellent new post summarising the changes and their affect on apps using beacons.
The article differentiates between Core Location and Core Bluetooth. Core Location implies using the iBeacon APIs while Core Bluetooth is lower level and allows scanning and connection to any Bluetooth LE devices, not just beacons (but perversely can’t scan the iBeacon UUD, major and minor). If, as we recommend, you use the Apple Core Location APIs directly, only the Core Location permission changes will affect you.
There was time, during the release of iOS 10 when Core Location beacon detection was faulty. At that time, Estimote decided to create an alternative beacon detection API based on Core Bluetooth to circumvent the problems. This means that if you use their SDK, users of your apps will get both Location and Bluetooth prompts and both permissions are required for the Proximity SDK to function. The iOS 10 triggering problems have since been fixed.