What the heck are you waffling about? Liz Truss caused the bond yield to spike. The sustained, long term level of the bond yield under Labour is now higher than it ever was in that very short Truss spike. Because Starmer's Labour are perceived by the markets as being less competent than Truss was.
Burnham's Labour party will be seen as a massive risk, so will make it spike much higher, to a point where the UK govt can't afford to pay the interest on its current debt, never mind borrow any more for all Burnham's fake promises.
Here you go, I've put a cursor on that Truss peak for the hard of thinking...
View attachment 416746
Have you not noticed that this govt has stopped mentioning Truss? It's because they don't want to be compared to her.
That most recent spike is the result of the possibility of Burnham becoming PM. As soon as he becomes an MP it will let rip.