I don't know about any evidence to support this claim. By law, industry will be shut down before any private home is affected. About 40% of gas and electricity is respectively used in industries. That means there is a lot of reserve before any home gets a blackout. Short term rolling blackout maybe, anything longer highly unlikely.

EDIT: Just saw the edit. Yeah, that doesn't seem like a big deal to me. In 2019 after a damaged cable, there was a 31-hour blackout in some parts of Berlin. In comparison a 2 to 3 hour one happens all the time during storms etc.