Girl I'm dating is considerably 'quieter' when we're in public?

When we're alone, she's very affectionate. She'll cuddle up to me and stuff.

However in public, or in a group setting, not so much.

She has told me she doesn't like PDA and that she's anxious, so that's probably it.

She has shown me affection in group settings, like resting her legs on my thighs, coming close to me...

Maybe it's just the not liking PDA. What do you guys think?
Girl I'm dating is considerably 'quieter' when we're in public?
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