I mean I love talking and all, I'm a yapper at heart, but I will only yap to people I am comfortable with.
Only close friends get yapping privileges. Everyone else is limited to one word answers and awkward laughter.
Also most introvert aren't shy per se it's just more of... ew socializing. Just the idea of existence near people especially strangers is enough to strike fear into an introverts heart. If I had to pinpoint a reason it's that I genuinely don't know how to talk to people. Like people are so confusing, you have to make eye contact but also don't do that too much or else you'll be creepy, stay engaging, but don't talk for too long or else you're weird now, oops. It's like, why did we have to invent a bunch of stupid rules for talking to people. Can we not just talk? Anyway it's just really draining to talk to strangers because of all the dumb unspoken rules. Especially I a group setting like, when do I talk? Did I talk out of turn? If I say something weird then I've embarrassed myself in front of a group instead of just one person. Talking to close friends is easy cause then you can just talk instead of walking on eggshells.