That's a good question Gail
My problem is I tend to forget the movies I particularly disliked And, to be fair, I don't often hate a movie. Usually it's more a "Meh" reaction.
That being said, the last movie I remember being strongly disappointed by -and even angry at- is probably Suicide Squad. I found it ugly, non-coherent, with bad acting, boring characters and bad rythm. I usually don't have super high expectations with superheroes movies, but with this one... I don't know. The concept was interesting and full of potential, but the result was a complete mess. A joke even, and a bad one. The fact that I had to pay an rather expensive cinema ticket to see it surely didn't help... But somehow, some people seem to like it. Good for them I suppose ^^ Everyone has the right to love or hate a movie, there's no accounting for taste.
I haven't watched Ad Astra, and didn't planned to, especially knowing your opinion about it now x)