Ultra Mobile interview questions

There's a total of 4 rounds. 1st is a phone screen, 2nd is with the hiring manager, 3rd is a technical, 4th is a culture fit interview. I thought I did well on the technical interview, and the hiring manager congratulated me on passing and explained what the next round would be like. Unfortunately, I received a rejection email a week later. Everyone I spoke to was super nice. I was emailed within a day of rounds 1 and 2 with details about the next round. When I didn't see an email after round 3, I sent a follow-up email to one of the TACs requesting guidance on timing. They were nice enough not to ghost me while I was sitting on an offer from another organization.