My basic setup is a NuxtJs App, a Hasura server, and Cognito for auth. I've setup a cognito user pool and client through terraform and everything was working fine. When I tried adding a login with FB, the pre-token generation trigger isn't fired, so the custom claims aren't added to the token.

The aws documentation for cognito didn't mention this, so have you came across this issue before?

Bonus: I also noticed that logging in with Facebook created a new user even if the email already exist for another user in the user pool, although the id and email are mapped to the cognito attributes username and email