Here is a quick reminder if you forget what the Fermi Paradox is: it is the apparent contradiction between the high estimates of the probability of the existence of extraterrestrial life, and the lack of evidence for this life.
A recent team of astrobiologists from the Australian National University have proposed a modification to the scenario. They call this hypothesis "the Gaian Bottleneck".
The Gaian Bottleneck proposes that, while many planets may have good conditions for the possibility of life, at some point they become unsustainable. The team pointed to Venus as an example of this.
Basically, any life that had or could have emerged who fail to adapt to the rapid changes and quickly become extinct. Basically, this hypothesis states that though life could have been possible, it is unlikely because extraterrestrial global extinction levels "are the norm, not the exception".
Thus, they believe that the mystery of why we haven't yet found aliens, or proof of aliens, has more to do with extinction than existence.