The previous Vic lockdown came after a Victorian done his quarantine time in SA.
That particular community case 0 tested early after returning to Vic and Vic like NSW thought they had the situation under control with contact tracing, it was around 2 weeks later after case 0 came forward for testing that Vic locked down.
It was also fortunate for Vic that during the lockdown they detected a Delta leak from a Melbourne hotel quarantine site.