It is. You want to send a boolean value but the editor changes it to a string.
You could open an issue but I don’t know if it will be fixed.
I assume it converts it to a string to prevent people using boolean states because this is a common error that prevents people from creating state triggers properly ( to: off is not the same as to: 'off' ) and similar.
It’s not a bug, that field accepts anything: float, bool, int, string, datetime. Because of this, it defaults the field to a string because the value can be anything and a string is the ‘best’ fallback. The byproduct of this results in the value being wrapped as a string in the UI. There’s no way around this, so you’ll have to use yaml for that service.