"Top-grade" Interview

Anyone else experience this type of interview style before? I just had my final round with a startup in my area and the last interview was with the CEO. I couldn't get a read at all and it was almost like he was just roasting my resume and experience for an hour. They kept asking "why" questions every time I gave an answer to one of their behavioral questions over and over.

My friend told me that this type of interview style is a thing at the company he works at so I wanted to see if anyone else has experienced this and if it's maybe a red flag for the company as a whole?