Night Light status is not updated after connecting a monitor
I have a second monitor that I usually keep turned off (I interact with it through Jonas Adahl's gnome-monitor-config tool because of unfixed gnome-shell issues).
If my machine goes to sleep in the evening - when Night Light is on - the next morning, when I turn the second monitor on, it still has Night Light activated, i.e. shows the characteristic red tinge.
Turning Night Light on and off doesn't fix it. The only way to fix it is to go into the settings, change the Night Light activation times to force it going into evening mode, and then resetting to the default schedule. Now both monitor are in sync.
I reckon that when a monitor is connected (via DBus or other), we should make sure to check if the Night Light LUT for that screen needs to be updated, rather than blindly restoring the state it was left in when turned off.