If you’re wanting to turn this into a clear warning, I’d avoid stating the claims about escaped victims’ faces being placed “on the black market” as established fact unless you have a reliable source for that specific claim.
A more accurate version would be:
Paris is an incredible city, but like other major international destinations, it has risks that travellers should take seriously, including exploitation and human trafficking. Visitors should remain alert, especially in unfamiliar areas, avoid isolated situations, protect their personal information, and stay in contact with trusted people.
If someone believes they are being targeted or exploited, they should seek help from local authorities or a trusted organisation rather than trying to deal with the situation alone.
Claims that escaped trafficking victims inevitably have their faces placed on a “black market” has been verified by one victim who has spoken out about it.