The charts in the UK have become largely meaningless in recent years. As others have noted, there are relatively few actual sales, with most of the chart positions driven by streaming.
The UK charts have a complicated set of algorithms to attempt to keep things changing. One sale = 1, but you need 100 premium (i.e.paid) listens to equal 1 sale, or 600 free listens (YouTube/Spotify Free) to equal a sale. Then there's something called Accelerated Chart Ratio to keep backlist music from dominating the charts. After a few weeks, those 100 premium listens jump to 200 listens for one sale and so on. The ratio grows over time. In other words, it doesn't matter how many times you stream Harry Styles' As It Was, it shouldn't re-enter the charts. This ratio almost kept Kate Bush off number one earlier in the year when everyone started listening to Running Up That Hill after it was featured in Stranger Things. Because it was an "old" track, it needed vast numbers of streams to compete with relatively modestly streamed new tracks. They changed the rules for it to count it as a "new release" and it reached number one.
Another change is to limit any artist to a maximum of three positions. That means that Taylor Swift couldn't do in the UK charts what she did in the Billboard charts earlier in the year and dominate them with every track from her new album. Only the top three get counted.
All that said, there are so few actual "sales" that a concerted effort amongst activists can push songs by groups like LadBaby into the charts by getting people to actually buy the song. I'm not close enough to these things to know what they did, but I suspect it takes a smaller than you'd hope number of sales to get that uplift. Their YouTube channel has fewer than 5000 subscribers, which suggests it really is easy to juice the charts. (Another top ten track is F**k the Tories by K**ts - you can guess the missing letters - which is another "joke" entry).
The rest of the UK charts right now are Christmas songs that get enough streams, and basically no new sales, to lift them back into the charts. Hence Mariah Carey, Wham and the rest.
Looking at the current chart -
https://www.officialcharts.com/charts/ - there are basically songs from Taylor Swift, Stormzy and SZA all related to recent album launches. Then a handful of joke songs - with the remainder being Christmas classics. That's even though those old Christmas songs all need 600 premium plays or 1200 free ones to equate to one actual sale.
Once upon a time, the charts were a big deal, going out late Sunday afternoon and getting big radio ratings on Radio 1 and commercial radio (there were two different charts, with BBC Radio 1 having the official one). These days, they get buried in Friday drivetime. Kids do not sit around caring that much.
Adam