Hello,
The "opening_hours:charging" tag is meant to convey that the parking space is open exclusively for charging during 10:00-22:00.

This was meant to replace the previous tag 	"parking_space=charging@(mo-su_10:00-22:00)" as part of a cleanup of invalid values for the parking_space tag.

This city is the only location I've seen time-sensitive charging spaces for parking mapped on OSM, so if there is a more appropriate way to tag these stalls that's compatible with local standards and data consumers, I'm happy to revise!