EUR/AUD have been dramatically spiking higher at 12.59% for 1W expiries and 12.41% for 1M expiries.

Volatility smiles most frequently show that traders are willing to pay higher implied volatility prices as the strike price grows aggressively out of the money.
The current spot FX is trading at 1.5183, since we expect more dips extending up to 1.5103 levels in near terms, aggressive bears can initiate strategy using ATM puts.

But unlike a simple naked puts, backspreads have an extra long that has not only leveraging effects, a short option at a lower strike that caps your reward but also reduces the net cost of the trade.

So, the recommendation for now is to go long in 2 lots of 1M At-The-Money Vega puts that would function effectively in higher IV times.

And on the other hands, short 1 lot of 1W (1%) ITM put option that would generate assured returns on any abrupt rallies, even if it drifts sideways the premiums will wipe off on time decay.

The Vega would be at its maximum when the option is at ATM and declines exponentially as the option moves ITM or OTM owing to every tiny shift in IVs that will make no difference on the likelihood of an option far out-of-the-money expiring ITM or on the likelihood of an option far into-the-money not expiring ITM.

EURAUD ATM options would be far more sensitive since higher IV greatly increases their chances of expiring ITM which is why we prefer ATM strikes to adding more weights in longs of this strategy.