Botox reconstitution liquid appears to be yellow. I just 55 units of Botox injected today at a Medispa in Toronto.

The reconstituted Botox should appear clear. If you are concerned, I recommend following up with your injector. It can take up to 2 weeks for final results with Botox. Best, Dr. Emer

Yes I would agree this is quite concerning.  Botox that has been properly reconstituted should be colorless and completely clear.  I would be on the lookout for anything different in the region of injection, but most notably signs of infection ( redness, swelling, heat).  When you are ready for your next injections I would highly consider a different facility.  Even though you do not have "proof"  it is never a bad thing to voice your concerns to both the facility/provider and if needed the appropriate regulatory agency.  A provider would want to know that the experience occurred under their care.