It largely depends on a culture of the people you talk to. For many Java developers Backend means communicating with the database and application logic. But they would consider templating and other veiw code a "frontend work", even though it has nothing to do with the web browser.
However, if you talk to JavaScript developers many of them would consider all code that is executed in a browser "frontend" but would exclude any server-side templating, partials, etc.
Then, some of them would still consider ALL JavaScript code a part of Frontend, be it a browser code or Node code. This can bring up some fun conversations. One of my coworkers talk about server-side bits of project A a "Frontend" because they are written in Node, but considers same functionality in project B "Backend" because they are written in Python.
Oh, I also would like to add an anecdote. Several years ago I worked at a bank and we had a system with 2 components. One of them was written in Java, the other - in Cobol. Our management referred to the Java part as "frontend" and to Cobol as "backend".
However, if you talk to JavaScript developers many of them would consider all code that is executed in a browser "frontend" but would exclude any server-side templating, partials, etc.
Then, some of them would still consider ALL JavaScript code a part of Frontend, be it a browser code or Node code. This can bring up some fun conversations. One of my coworkers talk about server-side bits of project A a "Frontend" because they are written in Node, but considers same functionality in project B "Backend" because they are written in Python.