Admin can't load on heroku

Hello.

I have deployed on heroku and it simply doesn’t load /admin.
Repo resides in : GitHub - gulcinofluoglu/alternatixbackend

config/env/production/server.js ;

module.exports = ({ env }) => ({
  url: env('HEROKU_URL'),
}); 

config/middleware.js ;

module.exports = {
  settings: {
    gzip: {
      enabled: true,
      options: {
        br: false
      }
    }
  },
}; 

what to do? i’m new on these things.

Same error