Hey @krzysztofsalbut never come across this requirement before but off the top of my head there is maybe two ways I would approach this.
Every widget is an instance, which means you can add some configuration and customisation to the instance of a widget, without it being consdiered 'customisation' of the widget itself. It may be possible through a combination of CSS and scripting in the instance of the widget to identify the sys_id of the catalog item and then hide the attachment icons/buttons if that Catalog Item has been used.
Alternatively you will need to create a custom widget that you place on the status page, that simply runs a check every time. It will be hidden from users and just executes some code to check the catalog item and if the specific one is found, it will hide it.
