To the folks having problems with Night Mode (UPDATE)

[EarlG]

2. Thanks, those are really helpful

As is the info about this happening on your different devices. The fact that the issue is consistent for you on different devices implies that the folks having trouble with this might be experiencing an issue with their connection to DU.

Just out of curiosity while I'm still looking for clues here, does the problem only happen if your devices are connected to your home wifi? Could you try switching your phone to its cell connection, instead of to your wifi? That would force your device to connect to DU from a different IP address. If would give me further info, depending on whether the problem still exists or if it clears up when you do that.