People are often nervous, defensive and stressed out about flaws they have.
For example: they are short, they have a small dick, their breasts are too small, they weigh too much, they have a blemish...
If everything else goes well, many of these issues frequently wouldn't matter to their date. But people bring up their own flaws and then act weird about them. The social awkwardness of saying, "I know I'm too fat but please don't be a bigot against me" is a much bigger problem than an extra 10 pounds. Saying, "I'm going to warn you in advance that I have a small dick, but I'll be really try-hard to make up for it." is even worse. (They don't say "try-hard" in those words, but they say stuff which has this meaning and is unattractive for this reason.)
It's ironic because people create their own disasters by awkwardly drawing attention to their own flaws. Then they take that as evidence their flaws are a big deal, deal breakers even, and so they're even more worried the next time.
If you don't bring up a flaw, a lot of times it will never be brought up. Relax and focus on stuff that matters, not "flaws" that aren't even a big deal you're just worried the other person will care about. If you don't want someone to care about something, don't start talking about it!
The same issue comes up in other contexts. Don't have a lot of work experience when applying for a job? Or maybe you haven't already done work exactly identical to what this job involves. Or you had a 2 month break between jobs. Or you got a B in a relevant university class. Or you and your previous boss didn't get along. In general, don't mention it. Don't start objecting to yourself and telling them reasons not to hire you. Address it briefly if they bring it up, but often they won't.