The Drake equation is usually turned into the Fermi paradox via some estimations that show the average (mean) number of alien civilizations we expect to see is large (>1).
However, just because the mean is large does not imply that seeing 0 is low probability.
More concretely, suppose there were 10 possible 'parallel' universes. In 9 of them humanity is alone and in the tenth there are tens of millions of alien civilizations. The probability of appearing to be alone is 90% even though the number of alien civilizations we'd expect to see is in the millions.
Talking about the Hubble Deep Field kind of misses the point. The original Drake equation[0] estimates the number of alien civilizations in our galaxy. I probably should have used galaxies in my example, but left it with parallel universes as that is the common phrase.
How will their paper work if we confirm life on Venus, especially if it independently evolved.