These 18,000 are most likely employed somewhere else at 20-25% wage increase. Note that a different study didn't see a rise in unemployment: https://www.nbcbayarea.com/investigations/california-minimum... which means that these people affected actually got a better living standard.
This group is well known for bias, over and over through the years. Nothing they report should be taken at face value.
"A considerable amount of financial support for the Center comes from labor unions: According to federal reports, over the last 15 years it has received nearly $1.2 million in labor funding."
"The IRLE’s highest-profile researcher is Michael Reich, who co-chairs its Center on Wage and Employment Dynamics. Reich made a name for himself at a young age co-founding the Union for Radical Political Economics, with the stated goal of supporting “public ownership of production and a government-planned economy.”"