When I applied for my visa in 2019, i did not put my middle name at all. All documents I filled out do not contain my middle name.
But here is the thing. My middle name started to come up in my Aussie docs. When I applied for driving license, I showed my Filipino passport as identity evidence. So they put my middle name in my licence.
When I applied for my citizenship, they also asked for the middle name.
So now, after 6 years, I ended up having my middle name in all my Australian docs, including my Aus passport.