If you check my other replies in this thread, I've tried to describe why I feel the way I do. But if I may, I'd be curious to hear what you'd consider to be "embarrassing", not as an act but as a personality trait.

As an example, I believe to recall the first time I felt this way as a child, perhaps age 4 or 5. There was some sort of a meeting and somehow a kid felt prompted to go up to the whiteboard and start explaining everyone the Bionicle alphabet (https://bionicle.fandom.com/wiki/Matoran_Alphabet) with unreasonable enthusiasm. I was into Bionicles myself, but remember thinking to myself, "Don't you know how you look like? Don't you know that nobody cares? Have you no sense of how others perceive you? If I hadn't seen how this looks like, would I have done something like this eventually?". I don't know how others brush these impressions away with a "Good for him".

I used to have something similar to this, as a teenager. I pretty quickly realized I was drawing arbitrary lines delineating things that I found cool as being better than things other people found cool, treating other people's interests as somehow more embarrassing than my own even though I was a textbook cargo-pants-wearing wannabe-hacker nerd. Between that and my struggle with depression, I ended up deciding that it's more important to enjoy things than to look cool.

Anyway, to answer your question: I'm not sure there's any personality traits I would call "embarrassing". There are some I would call harmful, sure, and there are some that are associated with being socially inept or less cool, but I don't think there's a category of personality traits that are just embarrassing.

To your specific example: Being enthusiastic about things isn't embarrassing; it invites others to share that enthusiasm, either because of a shared interest or simply because watching someone be enthusiastic about something is enjoyable.