Most folks avoid that four cam engine.
It’s such a short run and Subaru then offered a more reliable 2.5
To me it had better be dirt cheap because you’re rolling the dice.
my opinion
Looks like the CV boot is cracked and slinging grease. Clear signs of it slinging out.
How old is the axle? Theres a very small chance it could be old grease we are seeing. Check the axle boot for cracking. Or give us closer pictures of the ribs/convolutions so we can look for a crack. If it is, Reboot or replace the axle.