Just because Hungary is a NATO member doesn't make all their troops and equipment NATO. E.g. if you're a soldier crossing into another member's territory, you need a NATO travel order to prove that your presence is warranted and actually covered under the treatment. And even then, Ukraine isn't a NATO member nor have they given a permission for NATO members to violate their airspace.

So what if a few NATO drones violate Ukrainian airspace.

Violating another country's airspace with military aircraft is pretty high on the don't do list; Ukraine could in return close its airspace to Hungarian aircraft