Starmer was already the most unpopular PM on record before the budget, and Labour's voting intention is the lowest it's ever been. It's just a really, really unpopular government so of course it gets a lot of attacks.
The public do not see or agree that they have done well in any areas, hence their appallingly low popularity. And that was before this budget announcement.
It does not take a crystal ball to understand that the British media, which are vitriolic on a good day, will have an absolute free-for-all. It's nothing new.