The infrastructure is newer, more people are switching to 5G out of necessity, and the influx of newer users is straining that infrastructure which is not prepared for it.

5G is supposed to have taken over the network frequencies of 3G (15MHz to 20MHz) from 800 MHz, 850 MHz, 900 MHz, 1,700 MHz, 1,900 MHz and 2,100 MHz bands. The problem with that is the higher the frequency used, the farther it travels through unimpeded space, but the lower it penetrates in impeeded space. 5G (1GHz to 6GHz) on the same frequency bands won't penetrate as far in dense urban population centers with large buildings.

So yes, 5G can send more data at a faster rate. But don't confuse bandwidth with signal clarity or penetration. Because higher frequency doesn't always mean better operation or even better transmission. The receiver also figures into what is being transmitted. You can have the biggest array with the highest UHF and if the receiver isn't in a place with optimal reception, or it's not built for that input it will mean nothing. That's the difference between Bandwidth and Frequency. https://www.pcmag.com/news/5g-is-here-but-how-it-performs-varies-widely-depending-on-where-you-live