Prime Minister Liz Truss resigned just after just 45 days in office, the shortest term in office by a Prime Minister. She was the last Prime Minister to serve under the rule of Queen Elizabeth. And because of the loss of Queen Elizabeth II, Truss was unable to do anything for 10 of her 45 days due to the mourning period. On September 23rd her financial advisor, Kwasi Kwarteng, made huge cuts in taxes and the economy went spiraling. And interest rates went up and inflation increased a lot. Truss never recovered from the pushback she got and ended up resigning. At the end of her service she had a favorability of -74%! And many of her campaign members left or got fired, which didn’t help her favorability. 

Cites

https://www.washingtonpost.com/world/2022/10/20/uk-liz-truss-why-how-resignation/

https://news.sky.com/story/liz-truss-becomes-prime-minister-of-the-uk-12691158