It would probably be most helpful here to share your full configuration. if you run nginx -V it should print the full config that nginx has in memory. There shouldn’t have been any configuration changes that would break between those versions, but it sounds like it might have a change in the directory structure of where it expects configs to be(sites-enabled is a “legacy” setup, while conf.d is the current standard structure).
When it comes to where you store your site static content, you can define where nginx looks for that content in the config. Just need to make sure that nginx has permissions to access the files.