I'm sure that's part of why, but the bigger reason is probably a more reflexive "well we switched more left and it didn't help, what if we go the other way." After a dramatic Labour win, they're just Conservative-lite. That kind of "well this didn't work, lets go the other way" response doesn't necessarily mean anything about any party's actual popularity.
Huh? Brexit materialized in 2020. Labour happened in 2024. Immigration going up between 2020-2024. Going down since 2024.
And that’s somehow Labour’s fault?
I'm saying that I believe public opinion on Brexit is unrelated to public opinion on Conservative/Labour/Reform. I also believe that public opinion on Conservative/Labour/Reform is unrelated to any particular policy positions of any of those three beyond "things were bad under C, lets try L" and then "things are bad under L, lets try R". That's my explanation for Brexit being unpopular, but Reform nonetheless performing well in polls and the recent local elections.
("unrelated" is too strong, but I think they're weak correlations)
Those two outcomes are not mutually exclusive. A first-past-the-post system can give the power to a minority, if the opposing votes are divided. In the 2024 elections, Labour got a third of the votes but almost two thirds of the seats.