URL forbidden(403)

Rececently I have deployed one serverless application in AWS server using next.js.
All is well on deploy, but when I access endpoint, as provided by node terminal, it shows 403-forbidden.
According to my first level finding, URL which create for any resource from S3 bucket did not append with “stage” defined with API.
Endpoint- https://vgfu6y3e0i.execute-api.ap-south-1.amazonaws.com/dev/
But static content URL of S3 is without “dev” :- https://vgfu6y3e0i.execute-api.ap-south-1.amazonaws.com/_next/static/6Pxbq0L6zHvMm2vyF5auS/pages/index.js