Despite the fact that some research has been done, it has showed no evidence that weightlifting at a young age has any impact on muscle growth (link down below). So it's basically a myth, a possible explanation to the origin of this myth being that short people probably self select themselvestl be weightlifters. So that shouldn't be the worry of any reasonable person.
As for possible future damage for her health, it's basically like a host of other activities, in which if your perform them with bad form or without proper guidance you're setting yourself for trouble.
So the real question shouldn't be if weightlifting at such an young age is good or bad for her healthy, but if she's being properly and responsible guided by her trainer and not lifting very heavy weights regularly. Remember that not even weightlifters lift at their max regularly.
https://pubmed.ncbi.nlm.nih.gov/17119361/
Note: And for the guys roasting me about the title of the thread, I've already correct myself in the first page.