I read so many topics on the net about what happens if there is the same mac address used on different computers on the same network but i would like to know what exactly happens if someone for example got my phone's mac address from a hotspot network and impersonated me, but i no longer use that network and instead i use the one at home for example. can that person still receive the packets intended for me or will it be useless?
The MAC address is used on the datalink layer, not routing layer. Simply put, this means when you talk through a router, the MAC address does not carry "through" it, and you cannot reach "back through" that router to the original host using just the MAC address.
So, unless the attacker was on the same network as you, the attacker cannot do anything to you. It will be useless.