Mirlas - Thank You for reporting this.
This is a bit dangerous bug if somehow you want to delete all actions & conditions concerning a variable by deleting the variable but decided to copy the variable before deleting the variable. And when you decide to paste the variable, this will make your entire project a mess. Good thing I didn't encounter this.
BTW (I like to share my experience with your .capx)... The bug also happen in these conditions.
1) With / Without the "Or Block".
2) Even just by copying the (to be deleted) variable and re-pasting the variable also produce a bug.
3)It also happens to any kind of variable names.
4)It also happens when dragging to duplicate variables.
5)It also happens even if the variable was deleted a long time ago.
6)The actions are also affected like the conditions.