API 403 - Token Validation Failed

Hey, I’m sending these requests and after running the code around 2000 times, I get the status code 403, and it says token validation failed, what does this mean and how can i fix it? my cookie is valid

block = session.post(f"https://accountsettings.roblox.com/v1/users/{followers2}/block")
unblock = session.post(f"https://accountsettings.roblox.com/v1/users/{followers2}/unblock")

I’m coding in python using requests
Thanks