Hey ​@j_hnny, thanks for flagging this! 

This is technically not a bug, but rather the current expected behavior.

Even if your theme is set to dark, the login page was designed to be a universal interface so it does not reflect any individual user settings until you are logged in. The login page will always display in light mode.

We appreciate your feedback though. We’ll pass this along to the team for possible consideration of an individual’s device or browser settings.

Sure, I would agree with that reasoning if it were not an operating system level setting requiring no user account to respect.