I'm pretty sure my A52 5G did the same. I was trying to set up a Bixby Routine (Now called Modes and Routines) so my hallway light smart bulb would turn on when I reached my home location. It never seemed to work and it appeared that the location function wasn't working when the screen was off. I tried automatically turning on Google Maps to keep my screen on til I got home. I had turned on the Bixby option to work with the screen locked too.
In the end I sorted it by creating a routine that turns on mobile data and location automatically for when I leave work, as this gave a perfect location result, and on reaching home, the routine for arriving at my home location and turning on the hallway light worked. Another routine, also activated when I reached my home location would turn on WiFi. Mobile Data usage was also very minimal, it made very little difference to my data allowance.
So could you use mobile data turned on, together with location turned on to achieve what you want? If you have downloaded a custom map area on Google maps it shouldn't use your mobile data.
I used Google Maps myself sometimes for navigation, but I kept the screen on, even though i ride a motorcycle and keep the phone in my pocket, and just use the sound in my earphones for navigation. I just had location turned on and it worked.
I haven't used Google Maps on my new A54 yet, but the same location routines work with the screen off. The only issue I have is that SmartThings won't turn on my light if the phone is locked, but a screen on time of 10 minutes and lock time of after 30 minutes fixed that.
Perhaps you could create a routine that when Google Maps is opened, the screen is automatically set to a minimum value. For example:
If Google Maps is opened, then.. wait 2 minutes.. set brightness to 10%. The brightness would be reset after closing Google Maps.
