this internet

The fine print and stuff negates the whole false advertising thing.

But even with that out of the question. There is way more at play then just a tower being loaded and that can statistically be possible 24x7.

A tower can have any type of fiber connection to it. Rather that is a 25mbps connection or 100mbps+ connection(s) to it. That fixed pipe is shared by all the companies that use that tower. Generally the companies will negotiate for a fixed amount of that pipeline. So depending on the pipeline to whatever tower you connect to you have a fixed amount. Then you have weather conditions effect lte signal, solar activity effects lte signal. A leaf can degrade that signal. So many variables come into play, heck even a microwave being turned on can cut your lte signal in half from the interference.

There cell maps generally give them a good idea of rather you will get signal or not but its not fool proof and doesn’t account for things like your wall interfering with the signal, line of site, ect.

Its hard to say about your specific situation without knowing more info and a screenshot from the tmobile apps cell signal info. A speed test doesn't really say anything other then your speed to the speed tests server is slow.

You could have been on something like band 2 with a 10bandwidth before and now its switched you over to band 12 with only a 5 bandwidth connection. Maybe you are now connected to a different tower altogether because the other is down for upgrades. Like I said its hard to say without having them stats of before and after.

The nice thing about it is that noone is locked into any type of contract. You can come and go as you wish if the speeds are not upto your liking. Generally they try to make sure that you will get atleast 25 mbps but reality is generally way different then that. I know some people get 5 mbps. Some get 250 mbps. Everyones spot is different and lte signal is no grantee at any one spot sadly. 

Its why when people have other internet options I tend to always say if you have some type of fixed line no matter the speed. Its generally going to be way more reliable in the long run.

We have both att fixed wireless and tmobile home internet as a backup for that.  The ATT one connects to a tower 23 miles away and averages a 83 mbps down and 42 mbps upload. The Tmobile Home Internet connects to a tower 2.4 miles away and gets on average 13 mbps down and about 6 mbps up.