Hi Olivia,
Yes, it is a red flag when you see someone’s Snapchat contact information, or any other contact information for that matter, in their bio.
This is often a way for scammers or people with selfish intentions to isolate you by moving the conversation away from the dating site to a different medium.
It makes it easier for them to control how the interaction goes. Without the distractions of a dating site, it is much easier to manipulate someone.