I bought a OnePlus 8 Pro 5G and can't seem to get a 5G signal on it. I've checked my phone options and 2G/3G/4G/5G is selected. If I manually look at available networks I can only see 4G variants, i.e. EE 4G, Virgin 4G etc.
I've also checked the coverage with your tool and it looks like this area is covered.