One example is a recent study of the Yugoslav economy and what happened after control of production was shifted to worker councils. Employment and growth plummeted.

"Amongst other things, these work councils were now free to decide on the distribution of income between wages and investment. In one sense, this policy change was a success: income per worker increased and wages became a bigger share of the economic pie. However, labour-managed firms seem to have reaped such rewards by hurting other members of the labour force, restricting the employment of new workers so as to limit the worker-based labour market competition that could scupper the wage demands of the 'insiders'."

https://capx.co/do-workers-need-capitalists-new-lessons-from...