Probably because of their ever increasing pandering to the right. The entire spectrum has been moved so far right by all the scaremongering, that a relatively centrist position ten years ago is viewed as far left by half the country these days.
I thought it was one I hadn't seen (Largely because it was positive!). That's government approval, and everybody hates this government at the moment. If you want to make a point about what people think about left and right then you probably want to look at all the parties - something like this, from the same source: https://yougov.co.uk/politics/articles/52795-political-favourability-ratings-august-2025 Labour are at -37. Whether or not you count them as a left-wing party (and I don't), that needs to be put against the others. Tories at -39, Reform at -24, Lib Dems at -4 and the Greens at +5. That looks broadly leftish to me.
That sounds like a really scientific and researched thesis. Loads of concrete evidence for that then. p.s. I'm very bitter and dysfunctional and my life isn't up to much. Just saying
No, it's advocated by people with a social conscience and an understanding of the diminishing marginal utility of capital.