Even though their original motivation was different, they still achieve the same effect now as bond purchases under the bond purchase program. https://www.rba.gov.au/speeches/2021/sp-dg-2021-05-06.html  17/26  5/6/2021  Monetary Policy During COVID | Speeches | RBA  There was some increased volatility in the bond market in late February/early March this year as bond yields moved higher.
Bid/offer spreads in the market widened, though much less than they did in March/April 2020. The Bank responded to this by bringing forward some purchases under the bond purchase program, by increasing the amount purchased at one of its regular auctions, buying $ billion rather than the regular $ billion.