When I mentioned that, it was for a company that got acquired by a bigger company. I can't give specifics with revenue / profits but it is a 10+ year old online SAAS business and all of their web apps are being served by Docker Compose with a non-trivial amount of direct customer facing traffic.

Lots of data, caching, web apps, background workers and lots of various API integrations. No fancy React front-end, no fancy crazy system architectures. Just a typical LAMP stack but running in Docker Compose, cranking away serving value to customers with very good uptime and a very low cloud cost relative to revenue. With that said, a managed database was involved but all of the web traffic was served by apps running through Docker Compose with a simple git push model of deployment that handled thousands of deployments over the years without much fuss.