From the article:
IF Metall workers in Sweden – where Tesla doesn't manufacture vehicles but has a number of repair and service shops – have been on strike since October after what they described as years of Tesla refusing to bargain with the union. IF Metall-represented employees claim Tesla hasn't guaranteed them good wages, a pension or insurance.
From a translation of the IF Metall website:
The employees at Tesla deserve nice and safe working conditions, just like everyone else in the Swedish labor market. IF Metall has therefore negotiated with Tesla for a long time. Unfortunately, they have declined to sign collective agreements and thus violate basic principles in the Swedish labor market. Therefore, IF Metall has been striking since October 27 at Tesla's Swedish service points and workshops.