While I can understand a desire to try to make money off of running a Mastodon instance – consider that you can host your own private Mastodon instance for about $5/month, which gives you effectively unlimited control and customization.
If you intend to charge $5/month or more for cosmetics, what additional incentive would users have to use your server instead of their own? If you charge less than that, are you sure you’d be making enough money to cover the extra maintenance and responsibility you’re taking on for it?
If you post a copy of your
docker-compose.yml
file inside a code block, somebody can probably identify the syntax error for you. Otherwise, the best I can do is tell you you can paste your YAML into https://www.yamllint.com/ and it will tell you if your YAML is valid or not.