You can see the volume ease up a bit in the beginning of the flag, but then pick up as it nears the top of the formation and blows through it. Quick rally, short pause, blast higher. Volume dips in the flag and surges on the breakout.
Volume diminishes during the pause and then rapidly expands on the continuation.
Volume decreases considerably in the flag, but the break to the downside is accompanied by a big increase in activity. After a month long rally, the market takes a five day breather and continues even higher. Volume dips briefly and then picks up on the breakout. After a near straight up advance, the market takes only three days before resuming the upmove. During those few days, participation drops off a bit, but comes back as the market explodes out of the pennant.