Like you were really looking forward to a movie but were immensely disappointed
For me: Mad Max: Fury Road, Midsommar, IT 2, Snowpiercer, and every Avengers movie I saw
I was expecting a lot when I saw them because of the hype/ratings but ultimately bored by the movie or just not that impressed
Bonus: Waterworld, I wasn't alive yet for that one so I couldn't be tricked into thinking it was good and being disappointed when I watched it years later but they wasted a really cool concept on that movie