You have to consider this along with what's sometimes called the toothpaste effect. Decades ago, there was a survey of how often Americans brushed their teeth. Everybody was happy to find out it was something like 2 1/2 times a day.. Then somebody calculated that, if that were real, we'd be using about twice as much toothpaste as is actually sold. Another survey focused on church attendance in an area of, I think it was, Ohio. One Sunday they actually counted the people in church. Guess what? It was significantly lower than the survey indicated it would be.
There is a chunk of the population that answers polls according to a perception of what they "should" say. My guess is that the older polls showing gay acceptance were examples of this, and that the Trump era has given people license to be more honest about intolerance.