All black holes eventually evaporate. They’re believed to emit radiation (Hawking radiation) in both thermal and gamma ranges. Also, black holes have magnetic fields, which, in interacting with the environment, can sap energy (and hence mass) from the hole. And we (I) don’t know much about how gravitational forces can figure in to such equations, especially when you start getting into such tiny quantum scales. In fact, most calculations start breaking down with such tiny sizes, and you can’t add much mass when the target is already so small.
“Every so often, a physics paper will appear claiming that black holes don’t evaporate. Such papers quickly disappear into the infinite junk heap of fringe ideas”.
-Leonard Susskind
even large ones? thought evaporation was limited to micro black holes.