the adjustment of these fly-bys are about independently confirming the phosphine presence, which might or might not indicate life (through unknown physical processes)
The original nature article says unknown geological forces or chemistry was a possible explanation too...which seems more likely. Unfortunately popular science articles are more likely to write headlines as "Aliens!" than admit ignorance of geology or chemistry.
So remember when you're feeling very small and insecure
How amazingly unlikely is your birth
And pray that there's intelligent life somewhere up in space
Cause there's bugger-all down here on Earth