Questions & Answers about После уборки в комнате стало уютнее.
Because после always takes the genitive.
So:
- после урока = after the lesson
- после обеда = after lunch
- после уборки = after the cleaning / after tidying up
The base form is уборка, but after после it becomes уборки.
Because в комнате shows location, not movement.
With в:
- в комнате = in the room, inside the room → prepositional case
- в комнату = into the room → accusative case
Here the sentence describes what the situation was in the room, so Russian uses в комнате.