You gave your honest opinion so I'm going to give my two cents as well: I don't think the problem is actually the tea XD. It's the writing.
Speaking for myself, I'm disappointed because the manhwa started out pretty good and the concept was fun and interesting, but now the tea scenes are getting repetitive and there's no solid storyline. I think possibly because the ML fell too hard in love too fast with the FL so there's not much development left, and the FL is amazing at everything she tries instantly.
So I love a good concept shoujo (it's more fun than just romance), but imo the story is becoming less and less interesting. But who knows, maybe other people will still love it and it's just not my cup of tea (pun intended) ╮( ̄▽ ̄)╭

the manhwa is called the duchess' 50 tea recipes not the duchess' 50 tea recipes and her BUDDING ROMANCE. it's clearly gonna be... about tea. if you don't like it, don't read it anymore. there's thousands of other romance manhwas to read :I