Found my 13yo has a secret TikTok account

Just discovered this through her iPad activity. She's been following trend creators and posting videos of herself dancing. She didn't tell me about it and I'm trying to figure out if this is a big deal or if I'm overreacting. Do I bring it up? Do I check it? How do I handle this without her thinking I'm invading her privacy but also being a responsible parent? This stuff wasn't around when I was a kid so I'm genuinely lost.