For me it is not fixed in Android 15 either, it is an annoying bug because my automation based on the location tracker just does not work properly anymore.
The location is only updated when you open the Companion app, or after 40 minutes if you do nothing. It seems that when your device is in lock mode nothing is updated.
My phone:
Pixel 8 Pro
Android 15
Wifes phone:
Pixel 8
Android 15
We have a Nabu Casa subscription