Can my employer withhold my tips due to the ppp loan?

My employer applied for the ppp loan and was approved on April 21. My employer reached out to us stating that we would be considered employed and that we would be getting paid a temporary base amount for the following 8 weeks. Cool! Now that restaurants are allowed to open, we are scheduled to open tomorrow evening. Even cooler. I am a bartender and I normally get paid based on my hourly and my tips, of course. However, because we are being paid that “certain” amount with the ppp loan, my employer said that they would be withholding my tips from me. Is this even legal?