way to see if my tower near me is 5G

Using Cellmapper.net and the CGI information from your phone (or, in my case) the T-Mobile Home Internet app, you should be able to find the T-Mobile tower that you're connected to.  But keep in mind that the Cellmapper app is not necessarily up to date.  Along the lines of your complaint, I recently observed a pleasant increase in my download/upload speed.  Investigation found that T-Mobile had evidently placed a 5G installation about 2 miles from my location and speeds were wonderful (this location did not show up on Cellmapper but I found the installation via RF direction finding equipment that I have). All was great for about a couple of weeks, but now the 5G signal is gone and the previous throughput from the LTE tower that I was connected to for a year went from an average of 15Mbps to less about 2MBps.  Since I'm in a rural location, the problem is probably an oversubscription of users on the 5Mb bandwidth of the LTE link.  So, unless T-Mobile reactivates their 5G, I'll be forced to migrate to another carrier, most likely to Starlink, where throughput speeds (so far) are much better than the regression in performance from T-Mobile.