Phone Suddenly Drops Service unless on Wi-fi! -S22 Ultra

I am having the same issue since like a month ago. I just ened up a call with tmobile where they did all kind of things. Restting the network, changing the e-sim card, and some other things and it didn't work. I went and factory reset my phone and it did't work. They contacted me with a Samsung technician and they had no idea what the problem could be. But he was like if you pay $600 and return your device we will give you the new one that came out today😂… So here is my issue with them. I am losing signal in places where I used to get good signal. For example at my brother's house. I used to get good signal there until a month ago. And the funny thing is that we have 10 lines in our account, on new years eve, we where at my brother's house and all the lines on my account had signal there except me. So i dont think it is a problem with thye tmobile tower other wise all the other lines on my account would lose signal too. So if tmobile or Samsung don't know what to do, what are we supposed to do? Is the only solution to get a new phone?