Austerity... well, yeah, probably almost no-one really likes austerity. But what's the alternative? The UK Government has a huge debt and an ongoing deficit that simply isn't sustainable. Something has to be done about it. Liz Truss and Kwasi Kwarteng gave us a very clear demonstration of what happens if you try to carry on as if the deficit problem doesn't exist.
In practice there are three options for dealing with a large public sector deficit; you either cut spending, raise taxes or grow the economy until the problem is eliminated. Obviously everybody prefers to go with option 3, and often it's the best plan even if involves making the deficit slightly worse in the short term.
Truss and Kwarteng clearly believed they were choosing option 3, but in doing so they actually very clearly made the deficit much worse in the short term, and talked in very general terms with no actual plan about how some heavily discredited economic theories meant it would all work out.
In the current situation, we don't have a lot of room for manoeuvre, and probably can't go for option three without doing one of the others in the meantime. The primary reasons for this are the massive build-up in the cost of debt finance caused by the policies of chancellor Rishi Sunak (uncontrolled spending on Covid and failing to refinance debt onto longer terms at favourable rates being the primary failures), the loss of tax base caused by the drop in the economically active population (this is probably around 50% caused by loss of EU migrants), the need to support energy prices, and the overall fragility of the economy which is long-term smaller and less capable of growing as a result of Brexit.
In practice cutting spending is also unlikely to be a good idea in social terms because quite a lot of people will die as a result, and in economic terms because it will kill off any real prospect of growth. The only real answer therefore is to increase taxes, and target those increases as far as possible at people whose economic activity won't be affected, or where it will trigger more desirable behaviour.