What was your ex's biggest red flags you've seen after the break up?

As soon as he broke the things off, he went to dating apps directly and started to look for others. He didn't give me a closure for months.

I created a fake dating app account and found him. He was lying about his age. Despite he was 29, it was seeming as 24 on his profile lol.

There were dozens of red flags during relationship but keep seeing different ones even after break up made me feel weird.