I’m having the same problem here, although with Microsoft provider. Everything is working fine on local but fails once in production, with the error described by OP: error=Grant%3A%20missing%20session%20or%20misconfigured%20provider.
On local Strapi is behind Nginx as reverse proxy.
On production Strapi is behind Nginx as reverse proxy and Cloudfront on top of that. I don’t know if that can be the source of the problem, but I am struggling to find the origin of the error…
There’s another post there: AWS Cognito as Authentication Provider: Grant Missing session or misconfigured provider error with a workaround suggested that didn’t work for me.
Any help is welcome!