As for Yunnan Tea, for a while there, every single 'recommend me some loose leaf tea' post on reddit was bombarded with astroturfing from Yunnan Sourcing alt accounts.
I don't doubt that a lot of it is just trends, though. Online tea discussion was a bit more diverse ~15 years ago when I found teachat. For example, Japanese tea and teaware was much discussed back then.
Personally I drink English style as opposed to gong fu. It's the flavor profile I prefer. Never milk or lemon or sugar of course. I do 1g tea to 100ml water ratio, ~350ml at a time, with 2 min for green, ~4.5 min for white and oolong, and 3.5 to 4.75 min for black.
And on a typical day I'll drink Halmari Assam in the morning, Chiran Sencha after lunch, and rotate among Oolong, Darjeeling, Ceylon (Vithanakande is the only top notch Sri Lankan estate I've had, perhaps there are others), Keemun, Yunnan, or China Green in the afternoon and evening.
What actually is 'British-style tea'? Any black tea, tea with milk and sugar, any non-gong fu prepared tea, any tea historically associated with British tea trade, any tea typically drunk in GB today? Seems to me lots of confusion is possible whenever tea is associated with trading and consuming rather than growing, harvesting, and processing. Certainly some weight should be given to the tradition of 'high tea' of which I know almost nothing. Is tea served in it exclusively milk and sugar infused or is that just an option for people not appreciative of the tea itself? I know the English 'working class' identifies with drinking tea. What type of tea is most consumed nowadays and is there a subset of 'gormet drinkers' worth mentioning?
Normally this means lightly oxidized black tea with a strong flavor. So heavier oxidation than a heavily oxidized oolong such as Oriental Beauty, but not complete oxidation, which tends to produce teas described by British tea-tasters as "dull", "soft", "stewed", and other semi-technical terms that point to too much oxidation for various reasons.
This is not necessarily tea from a former British colony, but often is in practice because of different standards used for Chinese black tea. Old-style Keemun is an example of a Chinese black tea that would be considered British-style -- people who are used to the lighter maofeng style tend to be surprised by the taste.
It is typically tea with a high plucking standard, although there is some leeway with Chinese teas; two-leaves-and-a-bud is considered the baseline for British-style teas. Sometimes Chinese-tea drinkers can be a bit incredulous that the fannings in a tea bag follow a two-leaves-and-a-bud plucking standard, but often that really is the case. However, while "tippy" tea is considered favorably, it won't be an all-buds tea. Russia loved this style of tea, but Brits thought it was too bland.
It is tea that has had careful crop management. Leaving tea to its own devices like with semi-wild "arbor tea" would be a very strange concept for these tea-makers, who associate this with poor quality and disease.
It may be from old bushes, but not because old bushes are prized. Old bushes are not considered to make tea that is better than young bushes, but the yield is typically lower. It is associated with poorer tea farms that can't afford to uproot and replant their 100+ year old tea bushes.
It is fresh tea. People who are used to Chinese black teas seem confused by this, but a British-style black tea is considered at its best within months of harvest -- the idea of trying to casually sell three, four, or even five-year-old black tea like some Chinese-tea vendors seem to do would be very odd. A big part of this is that it is hard to get a tea of sufficient briskness to handle milk or sugar if it is too old, and the industrialization process that allows mechanically rolled tea to be affordable often reduces the shelf-life somewhat.
It is well-fired, but with particular attention paid to avoiding any burnt or char notes. Lapsang souchong has a few fans, but this is more of a revival of an older British style; by the 1950s hardly anyone was drinking that type of tea, although I don't think it ever went extinct as a style in the UK. The idea of giving a tea a rough and heavy char and then letting it sit for a year to allow it to go a bit flat and the burnt notes to fade would never be considered the way it is with some oolongs.
There are certain things which are important but normally fade into the woodwork with British-style teas, such as whether the tea is authentic, because of strong supply-chain controls. That is why there aren't yearbooks sold by manufacturers with pictures of the tea that they have made that year and their authorized packaging. This is also (I think) why British-style tea is more comfortable with smaller sizes of broken leaf, as there is less worry about malicious blending.
British-style tea is not normally very Instagram-friendly; the pretty Ceylons mostly go to the Middle East. It is not really a custom to look at the tea leaves, possibly because there is no need to verify that they are what they say they are, leading also to the loss of appreciation for the aesthetics of a good roll.
Stereotypically it is associated with vertically-integrated tea farms, but that isn't really true, as China still has nationalized tea farms, and some British-style tea is made at "bought leaf factories", where they buy raw tea leaves from whoever shows up, provided they meet certain standards.
Brewing-wise, it is tea that can be oversteeped; even when the teapot started to fade away, what replaced it was not a drinking-gaiwan type arrangement but some other way to quickly remove the leaves from the steeped tea at the right time, such as a tea-basket or tea-bag.