There are a few plugins that look a little out of date. You could try swopping those out and rebuilding.
https://github.com/paviliondev/discourse-follow.git is now an official Discourse plugin - https://github.com/discourse/discourse-follow
https://github.com/discourse/discourse-voting.git has been renamed and is now https://github.com/discourse/discourse-topic-voting
And https://github.com/paviliondev/discourse-tc-topic-list-previews is a theme component, and shouldn’t be installed in the app.yml