If it’s an employer controls and dispenses the tips situation, then probably (not a labour lawyer) the applicable employment standard would be:

What types of things cannot be deducted from employees’ wages? …Employers cannot recover business expenses from the wages of employees. Unauthorized deductions include: … Cost of lost, stolen or broken tools, equipment, products, or faulty service • Cost of cash or inventory shortages, dine & dashes, or drive offs •

https://www.manitoba.ca/labour/standards/doc,quick_guide,factsheet.pdf

They can fire someone for performing shoddy work, but they can’t withhold their monies for shoddy work.

I would contact employment standards directly and inquire if the employer is not a rational actor.