I meant "just a text editor" in the sense that it's not a full IDE with compilers and build system, versioning, project management etc. But now with plugins Kate does these things too
I use Kate mostly for config files or interpreted code like python, bash etc, and just launch the code from the terminal (or Kate's built-in terminal 🙂 )
For compiled code I like KDevelop, if that can be considered lightweight. Vscode / vscodium is nice too but not exactly lightweight by many people's standards (though I haven't tried it with compiled code)