Tenet?

I also didn't think it was that confusing. It was at first, while it was meant to be, but it explained enough that I could understand roughly what went on by the end. Maybe people don't like not understanding everything perfectly. Though I also don't remember people hating it, so maybe different movie.

If you're talking about Tenet, people didn't find it confusing because backwards moving time is confusing. They found it confusing cause 90% of the movie is overexplaining the concept through unintelligible dialogue, using a menagerie of unnamed characters in unexplained settings to deliver said dialogue.

That movie solidified in my mind that Nolan has surrounded himself with yes men and has lost the touch. A warning I should've heeded before I wasted my time on Oppenheimer

Tenet? If it is that one, I also enjoyed it

As others have said, you're probably thinking of Tenet. I watched it and by the ending I was a bit confused but thought the point of the movie was to be confused on the first watch and the second watch will explain a lot more. NOPE. I watched it again within a week and nothing that is explained in the first half holds up in the second half. They explained the rules and then ignored them to push the plot along. Great idea, very bad execution though.