tmobile is hot garbage!!!

There are several factors that determine the quality of your service but the main things: what rate plan you are on, what phone you have, what area you live in. 
For example, if you live an area with excellent coverage, have a iPhone 14 or S23, and are on Go5g Plus or the now grandfathered Magenta Max then you are going to have the best possible premium data experience possible because these two plans are the only plans ever offered by any carrier that is truly unlimited without throttling. 
If you live in the same area, with the same high tier phones but have Essentials then your service experience will be significantly lesser quality than compared to Go5g Plus or Magenta Max because this rate plan throttles (slows down) at 50gb of data used. Unfortunately every single carrier's unlimited service throttles with the exception of the two T-Mobile plans mentioned. 

If you live in an area with excellent coverage and have the best current plan but you are using a Samsung Galaxy S10 or lower or iPhone 11 or lower (these issues aren’t limited to just Samsung or Apple it is applicable to any older device) then the network issues you are experiencing are likely to be caused by the phone you are using. 
 

Plain and simple is you really do get what you pay for.