Unable to answer "What are the opening hours here?" – Biały Domek (Restaurant) – https://osm.org/node/3871225410 via StreetComplete_ee 57.0:

It's just someone's house. Maybe there was a restaurant there at one point, but there are no signs of it existing anymore.

Attached photo(s):
https://westnordost.de/p/207044.jpg