Are these natural? Or, what would you say?
I feel ashamed of talking in front of the community.
I feel ashamed of talking in front of the public.

Question

Answer

It depends on how your feelings relates to the action

I would say either: "I am too ashamed to speak in public"

or "I am ashamed when speaking in public"

Ashamed might not be the exact word you're looking for, maybe "nervous" or "shy" could fit better

Example: "I get nervous when speaking in public"

Answer

embarrassed