"In 2010, 39% of Americans agreed with the statement, "Men have it better than women." In 2020, the number of U.S. participants who believe men have it better rose to 57%."

"Gender equality is improving, yet society believes it is getting worse."

Maybe the first quote does not mean the 2nd one? Maybe now more people are aware of the gender inequality than the previous generation, and hence the difference in the percentage? So, society doesn't believe it's getting worse. Because the people who responded to the survey in 2010 are not all the same people who responded to the survey in 2020! Surely, some young people from that generation is still in 2020's survey, but some old people from the previous one are not in this sample space, while many new people from this generation are there.