Yes, upon checking Taal Volcano about 80km to Manila's south erupted at some stage on Sunday, later in the day.
Flights into and out of Manila NAIA were suspended - cancelled - from 1822 hours on Sunday 12 January for arrivals, and from 1900 hours on Sunday night for departures. QF20 departs daily at 1900 hours, so that is why it may depart tonight. MNL airport reopened midmorning on Monday 13.
As of about 1000 hours Philippine time on Monday, about 200 flights have been cancelled.
I am in Manila, transiting. The 'smog' (ash etc.) is noticeable from high up, but many residents and visitors are yet to don face masks. I visited three pharmacies this morning: two had sold out of all face masks, although one had children's masks available. Weather yesterday early arvo was beautiful but not so today.
At least 6000 residents have been evacuated, a wise move. Taal is close to the usual flight paths to and from Oz. i have hiked on its island but it is now a no go zone. There were also some minor earthquakes reported in the area.
Just as there has been in lower east coast Oz due to bushfires, expect a rush on face masks in MNL as air quality deteriorates. School classes have been cancelled.
The Filipino seismological institute has warned of a possible imminent explosion. Were this to occur many aircraft between Oz and HKG plus mainland China and of course Philippines would have to divert, or in some cases further flights might be cancelled.
Competitor PR207 operated normally on Sunday 12 January, departing MNL two minutes late at 1647 and ariving MEL on Monday 13 at 0401, nine early, but it was scheduled to depart 135 minutes earlier than QF20.
Expect chaos for MNL flights for the hext few days, given ongoing cancellations and a large passenger backlog.
Ash apparently reached MNL NAIA's ramp area but by Monday midmorning had been cleared.