Fun fact: to feed an adult, you need about one human body per year in terms of calories. In case of soylent green, every year one half of the population would have to eat the other half.

The movie Soylent Green is based on the Harry Harrison novel, Make Room, Make Room! which is described on Wikipedia:

Set in a future August 1999, the novel explores trends in the proportion of world resources used by the United States and other countries compared to population growth, depicting a world where the global population is seven billion people

This wasn't exciting enough, so turning Soylent Green into people meat was added to the movie for extra drama. Normally it's soy and lentils, ergo Soylent

In Bladerunner 2049 bugs are farmed for protein, but we already eat bugs in additives which only offends religious people. And ever since the spice Melange turned out to be fermented worm shit, intentional food processing nightmares have been more subdued.

However, in The Jungle documenting pre-PFDA meat production, rats, rat-poison and the occasional accidental fallen millworker all find their way into the sausage. It's why you don't want to know how the sausage is made.