This is a multiboard mount for the Zigbee 3.0 Sonoff Dongle (model ZBdongle-P from 2020).

It has holes for the aluminum heatsink on the front, but in order to minimize print time and material used for supports, the print orientation made it fill the holes in. If you want some heat dissipation, get your favourite screwdriver, a drink, and start poking.

Link to the dongle used: Sonoff Zigbee 3.0 USB Dongle Plus