Candle patterns are how retailers get lured into the market and stopped out.
The pattern in itself is meaningless. That could also be a bearish Harmonic continuation pattern setting up. Context is everything.
As it happens, I was long the GBPUSD at that point and still am long, but my trade parameters could not be described from that chart, and shock horror, look what happened to the ‘bull flag’ traders, only for the market to jack knife back up…
…also, as other’s have said, a flag would ideally be in the prevailing direction of the trend, but even then, the chances that the bottom of the flag (where everyone’s SL are) are also a meaningful well resolved low are generally quite slim, and more often than not, the text book pattern will simply lure retailers in, to provide liquidity for the bigger funds.