> Are you checking random SC notes in your free time, Mateusz? 😬 

Yes, this allows to catch some issues which noone reported (or to confirm that some assumption being made were valid, for example I declared that I will verify whether asking for detailing surface=unpaved/paved will result in avalanche of notes) 

> What would be the tag the description gets put in? 

Note that in general you can disable automatic upload in settings (or disable internet connection), make edit and undo it - it will show you tags being used.

https://wiki.openstreetmap.org/wiki/StreetComplete/Quests also lists tags and it claims that https://wiki.openstreetmap.org/wiki/Key:surface:note is being used