Did Rain Oversell their 5G capacity?

Rain 5G Internet service went from excellent to very, very slow. My Rain unlimited home 5G premium internet went from download speeds of 200 to 300 mbps down to 30 to 50 mbps download and between 1 and 5 mbps upload speeds in 18 months. Logging calls with Rain have no effect. In two weeks of multiple calls, nothing happened other than an auto reply, not even a comment from Rain. My guess is that Rain oversold their capacity and now have too many users, since the speed do pick up in the early hours of the morning. Either way, since one can now get better value for money elsewhere, in my opinion it is time to change to another service provider.