Recently, I had a look at a 5G coverage map for my local area, and was disappointed — but not surprised — to note that it was still patchy. Meanwhile, 4G coverage is pretty solid.
We've been here before, of course. Back when 4G first launched here in the UK, there were reception problems in many places, particularly so outside of urban areas, but even within buildings on some networks.
But it appears that nobody ever learns, because I see and hear advertising for the latest phones that always, without fail, mentions 'with 5G'. I suspect that most of these handsets will be spending the next few years connecting to 4G most of the time.