A similar one is being sold on
ebay as "Hungary 1914 3k Revenue Used - S32769"
So, if the vendor's correct, yours is also a revenue stamp.
You can use a screen capture and Google Image or Google Lens to identify stamps. Doesn't work on people, or statues of people- I spent a couple of hours yesterday trying to identify a C19 bust of a Victoria Cross holder. It used to, but then Google stopped it (privacy concerns).