I build things in my testing place, then transfer it over to the main game. The lighting settings are identical, yet the testing game looks much brighter than the main game.
One of those could give the same result. If that is the issue, though, you can’t do anything about that cause that’s just how Roblox works. It changes graphics APIs based on the device, as that’s how devices run games.
Toggle LightingStyle twice on both of them and see if it changes anything. If it doesn’t, then, well, just save the rbxl and upload it to the other place and it should just replicate them.
I found the problem. The main game had the Use2022Matierials property disabled on MaterialService, while the tester game had it enabled. This made some materials look much darker.