Not sure you can point the fingers in any particular direction to be honest, the criticism is coming from all sides and a lot of it is just points scoring nonsense.
The £200 to an awful lot of people amounts to no more than an unnecessary gift of public money straight in the back pocket. I’m not sure why anyone left or right wouldn’t want that stopped with those resources better used elsewhere. I’d imagine Starmer considered the changes common sense and would present as a Labour government showing prudence, but sadly when there’s a screaming headline or an opportunity to tarnish, the days of hoping for a reasonable debate around where the qualifying threshold might be set are long gone.