Underscore "_" cannot be entered when adding a property in the Properties tab

When creating a new property in the Properties tab, "" cannot be input, therefore, the user cannot input a name like "fav_contact_size." I'm pressing Ctrl + "" but it didn't work. This should be possible.

property int fav_contact_size: 3 

However, in the Properties tab in the Connections tab, you can input "_" in the property name you are about to add.