The downside of this is that by using the “delete all unused variables” button, it’s removing variables that are actually in use, in this case, the one I use in the validation rules.
Thanks for this question, this is a really good observation.
Are you by chance still on r274 (or one of the point releases of r274)? I ask because this has been changed to have the input widget validation variables marked as used in r275!
You will be automatically upgraded to r275! The way we roll out releases means some folks get the newest releases sooner than others, but it will be coming your way soon