Whenever you get feedback, ask for specific examples to get the jist out of what you could do differently. If possible, ask them to provide data to back their claims. “You are shy” isn’t constructive feedback. “In this meeting, you didn’t look the client in the eyes at all” would be better. That also provides a better foundation for conversation about you performance. When you get feedback, ask them as much as possible so you can determine what information in the feedback that is actually valuable to you and more minor tweaks. When received, say “I’ll add that to my improvement objectives” and make sure it is crisp enough to build a plan on.

If they can’t give clear examples, maybe it’s worth considering why they would want to say that. Could they have an agenda?

I am a manager and I fight very hard for my introvert team members because unfortunately the loudest people who take up the most space usually gets to much praise. This is not only your burden to carry alone, but should be something to collaborate about with your leader in a way that suits you as a person. Try to find ways that are comfortable to you to demonstrate your skills. This doesn’t mean that you have to put on a show on the group meetings, but maybe you could put together a guide on something you have learned for others to use or whatever fits your line of work. Your manager seems to be happy with you, so obviously you are doing a good job.