Had an interview at Company A, which in itself was a bad experience. 5 people crowded into an office with printouts of my response to a 20-question tech challen

Had an interview at Company A, which in itself was a bad experience. 5 people crowded into an office with printouts of my response to a 20-question tech challenge, implying I'd had help with it/cheated. I was invited back for an "extended interview" on a Saturday, "compensated, of course", where I did sysadmin stuff including setting up a work email for myself. Taken out for lunch by the guy running my "interview" who bought me a burger, and said "He (the CEO) is a bit cavalier in making promises, so I want to make sure you get something out of today". So basically I was paid a burger to onboard myself on a Saturday. A week later I'd received an offer from elsewhere, informed Company A, and got the saltiest email from their CEO about my unethical behaviour.