Many of the new apartment buildings have a large number of small one bedroom apartments, that have been sold to investors. These investors are hoping to rent them. In the past, a one bedroom apartment gives a good rental return relative to purchase price.
However, at present, there is a problem. There are too many one bedroom apartments. Owner-occupiers prefer two bedroom (or larger) apartments or houses. There is less demand for short term rentals at present, where a one bedroom apartment was a good alternative to a hotel room. And most young Brisbane renters prefer to share and rent large apartments or houses.
Some one bedrooms are sold without a car park, making them even less attractive. In my view, a one bed with no car that is 60sqm or less in size is worth about $310,000.
If rents go down, which they will, then capital values will fall.
There may be one exception here. Some of the riverfront older apartments, which have larger apartments (e.g. a one bedroom over 70sqm) seem to be holding up well. See for example this apartment and this apartment in Admiralty Towers