Cell towr metrics?

Unless you are pretty close to a tower with an unobstructed line of sight between it and your location, you're not going to get a perfect signal. I'm about 3 miles away from the towers in my area.

Your primary signal is a 4G signal, and you have to have one for service. The secondary signal, if there is one, is a 5G signal. At some point T-Mobile may deploy stand-alone 5G, but until then you need to have a 4G signal. 

The metrics you listed for your primary are ok. Based on the charts I've seen you would think they are just borderline, but they're in line with what I get on my primary signal when I'm only connected to 4G. And I get 90 to 130 down and over 5 up reliably. 

Sometimes my gateway will switch bands and/or towers and I'll get a secondary 5G connection with metrics similar to yours as well, though the 4G signal will be slightly worse. Then I'll get 150 to over 200 down and 20 to 50 up, though I generally wind up soon getting switched back. There's a chance that's happening to you as well as the gateway looks for the strongest signal. 

My ping times are regularly under 50, though jitter seems more inconsistent but usually under 10 (I'd really like to see that improve). I've gotten them to their best by concentrating on adjusting the device's location and orientation to get the best 4G signal I can, paying most attention to RSRP and SINR (SNR).

After spending far too much time moving and rotating the device inch by inch chasing a 5G signal that inevitably comes and goes, I’m ok with just getting a fair to good, but reliable 4G signal with speeds that are pretty good for a far lower price than the competition is offering.

(I'm sure Comcast Xfinity will offer a deal when I call to cancel this week, but they are losing my business for repeatedly telling me there are no better plans, and I'd have to go six months without service before I'd be eligible for any advertised special rates. T-Mobile would have to punch me in the mouth before I'd go back to Comcast.)