Doesn't really make sense that it's a data plan problem, 5G supposedly has higher capacity, so the plans should give more data and the fair use cap should be accordingly higher.
Also, isn't UK's 5G provided by the self-proclaimed world's first, Huawei, who's "a year ahead of everybody else"? So this is the 5G quality to be expected "in a year"?

Of course it's inconsistent - it's wireless :)
That's why even at potato-quality streaming for clients(no more than 10Mbps) we ask sternly for wired, preferably separated, connection - because for last 5 years, whether it's 3G, LTE or WiFi we haven't been able to to make any live streaming(most of what we do is streamed for over an 1hour each time) with no hangups/slowdowns/cuts - especially when you have to compete with who knows how many devices around you for the same piece of cake.
On paper, in short tests(speed test, etc.) we always get nice speeds, but it does not translate to longer data transfer.
(BTW, standard for TV is SDI connection - 1.5Gbps from single camera if you're going for full HD 25p/50i)

No wireless technology will ever come close to the quality of cable/fibre connection.