I was inform that you cannot tan/or be in direct sunlight after Brazilian Butt Lift/Liposuction is that true?

Tanning is not harmful to the fat grafts or the areas of liposuction.  Tanning is overall a poor habit for good skin health and more specifically it can darken the small fat grafting and liposuction incisions.Earl Stephenson, Jr, MD,DDS, FACS

You must avoid sun exposure or Tan after any surgical procedure for a certain period of time, depending on the procedure. In your case, for a period of 3 months.

You can tan, just remember, fresh incisions should be out of the sun until thy have matured. Friends don't always remember everything correctly. 

The main issue with sun exposure is that the incisoins used for injection and harvesting can be sensitive to the sun and sunblock over these areas should be applied.