The managers at my gfs job take a portion of their tips every shift. Is this illegal? What can be done about this?

My gf works in a recreational marijuana dispensary in Colorado, and has been employed there for a year. The whole time, all the tips they receive in the tip jar are divided equally between all the employees currently working, including the managers. My gf just did a google search and it says that managers taking tips is illegal under US law. Does anyone here have any clarifying info about this?And where can we report this? Thank you if you read this 😀