Candidates: you need to appreciate how difficult it is to hire good people, the dishonesty of many candidates, and how limited the tools are for identifying talent and filtering out weasels. It is true: party trick Big O questions have low utility in most jobs. It is true: there is talent out there which sucks at Big-O questions. It is true: there are people who are good at little else than the party tricks. Nevertheless: those questions provide an objective judgement about a candidate. That objective judgement is valuable.
You spent several years doing a degree to make yourself employment-compatible. You will be able to achieve this standard in far less time, and there are cash rewards at the end of it. Accept that you will need to burn 1-2 months to develop this capability, and that you will feel awesome once you have.
Get /Cracking the Coding Interview/. I was not impressed by the object-oriented design chapter, but seek to master the other first-11 chapters. Take what you need from the remaining chapters. Develop a set of flashcards. Find problems online. Work intensively for at least two weeks but ideally a month. Then book some interviews at firms where you don't mind if you fail. Some of the FAANGs have awesome pre-interview study material. Try to get into process with a firm like that. Keep training on your flashcards and doing a few problems a day to keep in form. Expect to struggle with early interviews. Learn from those experiences. Revise what you made a mess of, keep working with your flashcards until you have mastered your weak areas. Now start applying at the firms where you want to succeed.