Carbon Fields when required by Composer needs to live in the public WP directory. You can fix that easily enough here: [https://carbonfields.net/docs/guides-bedrock-support/](CF + Bedrock guide). When deploying with Trellis I started getting autoloader exceptions for Carbon Fields from the wp-cli during the deploy.
Finally figured out that Carbon Fields was not making it into the Bedrock web/wp directory on the first pass of composer install. I went into the site install and manually ran composer install and boom it all works since there is a web/wp to stick CF into when composer install runs the second time . I edited the after-build hook that calls composer install to simply call composer install twice in a row. I got it working, yet is there a better way to solve this issue?