Error 400112 "Unauthorized" when using /v2/video/generate with X-Api-Key

Hi, I’m trying to generate a video through the API from n8n using the endpoint:
POST https://api.heygen.com/v2/video/generate

I’m sending the following headers:

X-Api-Key: <my_api_key>
Content-Type: application/json

but the API responds with:

{"code":400112,"message":"Unauthorized"}

The API key is active and belongs to the same workspace where my avatars are located.
Could you please confirm if this endpoint requires a specific plan or permission?
Or has there been any recent change in authentication (Bearer vs X-Api-Key)?