Despite negative net overseas migration, Australia has seen a sharp decline in rental vacancy rates due to the pandemic.

The loss of hundreds of thousands of migrants should have led to Australia's rental vacancy rate going up. Instead, it went down.
According to one theory, Australia's desire for more space has led to a sharp drop in people per house, which has boosted rental demand despite slow population growth.
It's also possible that short-term rentals, like Airbnb, have taken homes out of long-term rental pools.
There are more Airbnb listings in New York than apartments for rent, says Curbed:
One in five Manhattan rentals (and one in three luxury units) are in bidding wars, according to the latest Douglas Elliman report. In April, there were just 7,669 units in Manhattan, Brooklyn, and northwest Queens. According to AirDNA, a third-party site that tracks short-term rentals, there are just a few thousand fewer available Airbnb apartments and homes in New York City right now: 10,572.t scrapes Airbnb listings, the number is even higher, at 20,397.
Since Airbnb came on the scene in 2008, there were concerns that the short-term rental company would deplete the housing stock by sucking up available rooms, leading to higher housing prices in cities like New York and San Francisco, where the housing shortage was already severe.
  SQM Research lists 12,758 rental vacancies in Sydney, while Domain has 12,461 available properties (every type of property except land):
According to these numbers, more than 60% of all properties in Sydney for rent are short term rentals.
It is obvious that this is a back of the envelope analysis that does not adjust for overlap between the two sets. It also does not account for the impact of Airbnb rentals prior to the pandemic.
However, it indicates that short-term rentals, such as Airbnb, are having a major impact on the rental market and are contributing to Australia's acute shortage of rental homes.