I'm not knowledgeable enough on the topic to say if this is a good or a bad decision.

However, decisions with major economic impacts should not be made by unelected boards in a democracy. Legislatures are excessively delegating their authority.

https://calmatters.org/environment/2023/04/california-phases-out-diesel-trucks/

California phases out diesel trucks: What happens next?

In a worldwide first, California’s air board unanimously ends diesel’s decades-long stranglehold on the economy. Truckers predict chaos.

CalMatters