TikTok Shop

I may need someone to explain this to me like I’m 5 but is she really making that good of money off the TikTok shop? All her posts on TikTok lately have been products she’s bought, reviewing and links. It seems like this would be quite costly (not that she cares how to budget or save money) or is she getting these items for free in exchange for making a video? We know she doesn’t get any legitimate partnerships.