Department of Home Affairs Immigration is responsible for Australian National Border entry conditions and this information is changing rapidly. You can keep an eye on developments here https://covid19.homeaffairs.gov.au/
You can use the VEVO system to see what impact things have on your visa specifically https://immi.homeaffairs.gov.au/visas/already-have-a-visa/check-visa-details-and-conditions/check-conditions-online
