https://www.epi.org/publication/union-membership-data/

Overall, it shows union rates being mostly a wash in 2023, but that’s due to a large increase in total jobs that year; raw number of members went up, rate slightly declined. Black workers made up almost the entire grid increase.

The point that maybe relates most to what OP was saying:

These statistics don’t capture the number of workers who want to join unions. Evidence suggests that in 2023, more than 60 million workers wanted to join a union but couldn’t do so.

This reply came more from the big wins Labor has experienced the last two years, such as the auto, rail, and writers’ strikes being resolved, not individual stats.

I think there’s also the problem of certain sectors of work, like tech or retail, which should be unionized but aren’t. Either because a lack of a history of unionization or because companies can too easily close a location and open another one across the street.