This appears to be an exaggeration that’s making its way around less scrupulous news sources. From https://www.euronews.com/my-europe/2023/12/30/was-oslo-paral... :

a spokesperson called the allegations “an extreme exaggeration… We cancelled, on average, between 50 and 100 departures, out of more than 4,000 daily departures, for a few days.”

The company did however admit they had a few “challenges with the range of the buses being shorter in cold weather."

"We solved this by changing the charging shifts. And also by fixing the charging infrastructure."

Ruter [the bus operating company] claims the issues have since been fixed and the fleet of electric buses continues to run as usual.