What do you refer to as "night mode"? If you are refering to Night light, the feature that tints your screen, then that is a simple, separate feature that doesn't have anything to do with notifications. Have you tried using Do Not Disturb mode?
I mean "Settings -> "Digital Balance & parental control" -> "Night Mode" and as I can see, it orchestrates both "dnd" and "night light", but it also has separate icon in quick settings, so you can enable/disable it all together