Such content included public health and safety information (government/emergency services advice re. the pandemic and bushfires), though Facebook later claimed this was a mistake and restored it (I don't know details of exactly what was removed and what has been restored).
It also included other content platforms - i.e., several major news/comment sites, satirical news sites, weather/climate info sites, retail sites, a major independent restaurant/cafe review site, and info services for minority communities like indigenous groups. I think most of these platforms would have attained little-to-no benefit from the new laws, so they are just "collateral damage", losing traffic and revenue over a law they likely didn't support and had little to gain from.
It seems highly capricious on Facebook's part, and a terrible PR move, given that most Australians probably didn't support the laws, at least not very strongly, but in a climate where people are already uncomfortable with how much power the major internet platforms have, this "show of strength" against a country's elected government and populace is alarming.