Fused location provider blocks, despite accurate GPS location

[ellenhp]

(originally opened here)

Describe the bug

Occasionally on /e/OS the fused location will take a very long time to update, despite the device having an accurate GPS location. My understanding of the Google fused location implementation is that fused location will always prefer GPS if the GPS is active for any reason, and I it seems wrong to me that the location fusing is blocked (probably by a slow network call) if the GPS is active and has an accurate fix.

To Reproduce
We have had issues reproducing this bug but I strongly suspect that it's due to latency in the network location API calls, so I would start by artificially introducing latency there to see what happens to the fused provider.

Expected behavior
I would expect the fused provider to emit GPS location updates despite the lack of accurate network location.

Screenshots
I'm having some issues with the attachment upload but there's a video here:

https://drive.google.com/file/d/1c-byuhu9xTzSe1CMrnIm2YsRG1_VpqsN/view?usp=sharing

In this video, the device is on a moving train as you can see from the GPS provider, but the fused provider gave a stale location from many minutes ago.

System
Android Version: 13
Custom ROM: e/OS 3.0.1

Additional context

[dimaryaz]

I keep seeing stale locations while using TransitApp while riding a train; this looks like the same bug.

[Sapiosenses]

This has been a longtime issue of mine since before UNLP was deprecated in 2023-05. (And I've brought it up here before several times)

If a network location provider has wildly inaccurate data, it often "poisons" a good GPS fix.

That should never happen. Because unless you're in a war-zone where the combatants are jamming GPS, a good GPS fix should always be considered the highest-reliability geolocation source.

But I've had multiple people I support mention this is happening again now.

Turning off all the options in the microG utility's "Location" section (except for Nominatum) always fixes the issue. (Basically reverts to GPS-only geolocation)