Northrop Grumman Principal Systems Engineer interview questions

Technical Interview over Zoom; Spoke about my previous experiences, non-technical questions at first then asked if i had any experience with MBSE. A panel about 5 interviewers. They also asked if I was interested in doing Cyber Security

First stage interview was to assess suitability for second stage interview, it lasted about 45 minutes and just asked about previous work experience. The second stage interview was about 2 hours long and was based on competency-based questions, based on the NG values e.g. we believe in innovation, give us an example of a time you came up with a new solution. The interviews went well, but they strung me along for months before withdrawing the offer. Every few weeks they would negotiate me down on salary, in the end it was nearly £10k lower than the advertised role. It's really upsetting that they operate like this, I have read it was a slow process, but this really took a lot of time and effort, I'm devastated that they treated me like this, over such a long period (4 months). I hope they don't treat everyone like this.