Heat pump

When the tech added refrigerant, where did he find the leak to be located at?
Refrigerant isn’t consumed during equipment operation. So if the unit was low then there’s a leak to be found.
It’s probably a problem with the heat pump refrigerant circuit, and the warmth you feel is the auxiliary heat staging in.

Sounds like you may have had a sales tech, someone that is payed to push new equipment.
Depending on how large the leak is the unit could be low on charge again.
How old is this unit? What refrigerant does it use?