I found this help article where they say “Although not all non-genuine supplies may cause quality issues”.

They said they recommend using theirs, but up until this they didn’t say you couldn’t.

support.brother.com/g/b/sp/faqend.aspx?c=us_ot&la…

Plus, it’s been universally understood that you have been able to use third-party cartridges. I really think if you’re persistent enough, you’d get a refund in Australia. Because else (in Victoria at least) you could take them to VCAT for like $70, which will cost them wayyy more in lawyer expenses than the price of a refund.

This is not legal advice, but I reckon a refund under Australian Consumer Law is extremely doable if they go down this path (for existing printers).