4G has been approaching 2 Gbps for several years, combining signals from 5 spectrum bands, typically 20 Mbps each. Most networks stuck with 3 or 4 channels because since ~2014, most telcos have had more bandwidth than they could sell. Most phones couldn't handle 5 channels until recently. The technology worked but was rarely put into production.
4 or 5 channel 4G was faster than most 5G, which added little or nothing to throughput. The recent speeds of hundreds of megabits have nothing to do with 5G. The large volume of mid-band spectrum delivers high speeds in either 4G or 5G.