Fastlane plugins not installed

I am using fastlane during my github actions builds. But since I added a new plugin, I started receiving an error:

It seems like you wanted to load some plugins, however they couldn't be loaded

This is my Pluginfile:

# Autogenerated by fastlane
#
# Ensure this file is checked in to source control!

#gem 'fastlane-plugin-json'

Here is part of the github workflow:

 runs-on: ubuntu-latest

   steps:
      ....

      - name: Setup Ruby
        uses: ruby/setup-ruby@v1
        with:
          ruby-version: '2.6'
          bundler-cache: true

      - name: Setup Fastlane
        working-directory: ./application
        run: bundle install

      - name: Build Android version
        timeout-minutes: 10
        working-directory: ./application
        run: bundle exec fastlane build platform:android

when it comes to the usage of the json plugin, I receive another error:

Could not find action, lane or variable 'read_json'.

which just confirms that plugins were not loaded correctly

Any ideas on how this can be fixed? thanks!