You might want to read about how to configure clj-kondo. These two sections might be of extra interest:
If you see clj-kondo squiggle the first character of the file with an error you don't quite understand, it is probably something wrong with your clj-kondo configuration.
The clj-kondo extension lints the current file as it is being edited. If you want to lint the whole project, use the clj-kondo cli command. See https://github.com/borkdude/clj-kondo for more info on that. Windows users might like to know that they too can get a clj-kondo cli command now, via
npm install -g clj-kondo. It'll be a bit slower to start than the native build, but for sure it's better than not having a clj-kondo command! (Besides, the VS Code extension takes care of the cases where you really want speed.) See https://github.com/borkdude/clj-kondo/blob/master/doc/install.md#npm-linux-macos-windows for more on this.