The scope of back-end development has grown considerably. In fact, it's precisely "one level of indirection" bigger: "commit is the new save", "push is the new commit", and "repo is the new module". Plus, "full-stack development" now includes containers and orchestration! Which is, of course, insane: distributed systems are, in general, not well understood. Expecting people to understand front-end, back-end, and then…
I have never met a full-stack developer that is comfortable with the full stack. I am also pretty sure full-stack was coined by recruiters and marketing folks to create a technical middle class.
I've met many full stack devs who are comfortable from DB (db design and stored procedures, sql) - backend code (java, spring framework) backend services (consuming first party and third party APIs) - frontend code (javascript, typescript, jquery, angular, react) - frontend services (Google analytics, GTM, etc. )
Edit: forgot to add in CI, CD, deployment platform skills, server less functions etc