Since the update to iodeOS 6.9, the automatic dark theme with location data no longer works on my Google Pixel8a.
Under iodeOS 6.8, the automatic change at sunset or sunrise had worked wonderfully.
The location services including BeaconDB as an online service are activated. Location Search via Wi-Fi or Bluetooth is also enabled.
I changed my settings so I can see if I can reproduce this: usually I have all dark mode all the time 
I am on a Pixel 7 Pro FWIW. I am using the position.xyz online service, not beacondb.net .
Having the same issue with graphene and l4m devices so I assume it’s an aosp problem
Yes, in addition to it not switching based on location “sunrise to sunset”, I also tested with a fixed time (e.g. dark theme from 11 pm to 6 am), and it also didn’t auto-switch. I’m checking with the team to see if they can also confirm.
I am pretty certain this is an upstream LineageOS issue. I created an issue on our gitlab tracker linking to a few of the Lineage issue reports.
I noticed that the night light (yellow tone) works automatically. It’s interesting that night mode itself doesn’t take this into account.
I would have liked to write this in the issue, but it seems that you can’t register there.
I think the “blue light filtering” is a bit different as it doesn’t switch themes, it just adds an overlay “drawn over the top” to yellow-ize the screen. I’ll add your comment to the issue however (yes, unfortunately due to limited oversight capacity our gitlab isn’t open for public registration).