Hmmm that's interesting. KSON actually shows a warning when there's misleading indentation, exactly to prevent this sort of thing! It seems like the detection logic only considers indents after a new line, so it doesn't complain in this case. I just opened an issue to see if things can be tightened up a bit (https://github.com/kson-org/kson/issues/221).
To see misleading indentation warnings in action, you can try the following snippet in the playground (https://kson.org/playground/) and will properly get a warning:
ports:
- 80
- 8000
- 10000
- 12000
- 14000
Next to that, note that KSON already has an autoformatter, which also helps prevent misleading indentation in files.