Without it there is no story but you're not supposed to care how it works.
https://en.wikipedia.org/wiki/MacGuffin
When Grace poked the astrophage with a needle and it disintegrated I couldn't stop thinking "Where did all that energy go?" Obviously that critter partially exists in dimensions we are not familiar with. Sure that's fantasy, like many of the "scientific" explanations in Star Trek, but it's not the point of the story.
A simple McGuffin usually doesn't interfere with my "willing suspension of disbelief" in a story, but when they get most of the science wrong for no good reason it completely ruins a movie for me. "Gravity" with Sandra Bullock and George Clooney was a movie like that. I can't count the number of television series that are like that, shows that are supposed to be set in our universe, here in our time, where the fictional scientists, engineers, or medical doctors in the story are spewing pure nonsense. If you were making a serious drama about professional basketball you wouldn't have the players running up and down the court wearing NFL football uniforms and protective equipment throwing a tennis ball around. Sometimes the science on television is worse than that.
In the Harry Potter movies the magic is the McGuffin. We're not expected to care much about how magic works, it's not what the story is about. I read most science fiction as fantasy, especially anything that involves human colonization of the solar system or interstellar travel.
I enjoyed Project Hail Mary. It wasn't the usual green-screen-and-CGI science fiction schlock.
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