Can’t help you with the tea question, or bergamot oil. I don’t drink tea, and have never heard of bergamot oil. Hope you can get some answers.
Earl Grey tea seems to be one of the most common types of tea you can buy. It has something called bergamot oil added to it, which I don't know very much about either, but I think I have read that it is a flavoring that comes from a kind of oranges.
Anyway, I felt better after I stopped drinking that type of tea. A main reason I drink tea is that I add butter to it, but that's another story.