Yes all countries do it, but US intelligence doesn't just take into account the action, they take the actor as well. Australia is a friendly nation to the US and shares intelligence data with US intelligence agencies. What we see, they see and what they see, we see. Russia is not a friendly nation to the US and does not share intelligence with US intelligence agencies.

The FBI isn't saying "normal people are at risk from FaceApp" but "US intelligence is at risk from the use of FaceApp". In the (very short) linked letter, it specifically calls out "elected officials, candidates, political campaigns, [and] political parties".

Considering all US intelligence agencies unanimously agree that Russia already attacked US candidates and political parties in the past, saying "yeah but everyone does it" is about as off-topic of a remark as you can get. To my knowledge the FBI has never publicly disclosed Australia's efforts to meddle in US elections.