Where nixos?

Yes vanilla is not plain. The plain flavour is Rabri. It’s just you don’t have rabri in the west that’s why you all think vanilla is plain.

Also rabri ice-cream >> vanilla ice-cream

Blackout curtains have different levels. From your comment it seems to me you probably tried 100% blackout curtains. Those are quite overkill.

You should try 80% blackout curtains, they block almost all of night lights and have a warm yellowish haze during the day.