Why are guys considered a "red flag" if they've never been in a relationship?

19M, I was talking to some random people on discord there were like 3 boys (including me) and 4 girls, and they were all talking about their last relationship, after sometime they asked me to share my experience and the second I said "I've never been into any relationship" 3 girls were laughing and said "Eww red flag".

My entire school life, I never had a girlfriend. Now, in college, I feel like I need a partner, but when I introspect, I realize it's all lust making me feel this way.
Did i miss crucial ingredients for a relationship?

Ps- For now, I'm not planning to enter into any relationship. I'm just worried about the future—will I be rejected because I've never been in a relationship?