I was testing Smarty as I was planing to move networks and noticed my phone was showing 5G (5G NSA according to Network Signal Guru, not "proper" 5G). They enabled it a few days ago.
AFAIK all networks use 5G NSA right now apart from a few trials. Its quite annoying as Three launched 5G here the middle of last year and during quiet hours:

However during the peak hours I get random bouts of high ping (much more frequently if you use their public IP APN
3internet rather than their CG-NAT APN
three.co.uk) and much slower speeds, almost certainly down to upstream contention as I got identical behaviour on 4G which is why I originally cancelled Three and moved to Voxi.
As I don't generally play online games though it has been a HUGE improvement for downloading games while keeping my typical browsing to Zen and AAISP L2TP over Libera 4G as the main backup.
Considering its my cheapest broadband connection, its kinda hard to complain but I wouldn't want it as my ONLY connection.
Worth noting, I'm using a Hauwei CPE Pro 2 H122-373 which is really pricey and seems to be constantly out of stock now. My phone could barely hold onto the Three 4G connection, a good router makes a world of difference especially as I have houses and trees between me and the mast. So its actually performing far better than I expected.