I very frequently misclick when trying to edit the Name of an Instance and end up clicking the Parent property instead. Then I will fix my aim and click the Name property, but because I have the Parent property selected, Studio will think I am trying to set the Instance’s Parent to whatever I click on. The Name property does not identify an Instance, so Studio will think I am trying to set Parent to nil. Then the instance gets deleted.
This can be easily undone by pressing Ctrl+Z, but it’s really annoying and confusing. I think if you are setting parent to nil there should be some kind of confirmation or notice to prevent confusion and mistakes, and also clicking with the Properties widget should cancel the reparent operation instead of parenting to nil.