Unless, for example, we were to find Mars had and has single cellular life. That might increase the likelihood that the filter is at the single to multicellular phase by enough to offset the bad news that the filter is not the abiogenesis step.

I think one thing to keep in mind is that we haven't been here for very long. And as a technological society that is able to be detected or detect something we have been here for something between 70 or 5 years or 0 years depending on the definition. So the great filter is something that hinders us to detect detectable civilizations. But we are at the moment not totally sure if we are already detectable.

So per definition the great filter has to be in front of us as long as we wouldn't be able to find ourselves.

> it necessarily shifts probability density into our future

why? if the filter is "move from unicellular to multicellular" it would have wiped out life on Mars but Earth somehow made it. It shows there's at least one step behind us which is "hard" (while showing there's another one which is "easy").

Yes, thank you for fleshing out what I meant.