That one theory to explain the Fermi paradox, I think it’s called the great filter.

The Fermi paradox basically says since that space is so big, there statistically should be an advanced civilization able to communicate/reach us but none have.

The great filter HYPOTHESIS states that since none have, one possible explanation could be that there is some barrier prevents civilizations from becoming a hyper advanced civilization. It could be anything from climate change to war, but some particular people say it could even be another civilization that stomps out life on other worlds once they hit a certain point in development to prevent them from becoming a threat/too advanced. This is most probably just sci-fi and some conspiracy theory sounding junk but it’s really cool/freaky to think about, because for all we know it could be true.