Why does the newest candle keep moving?
It is a minute that has already printed, being revealed five seconds at a time. Every price in it really traded, and your fills are decided on the same reveal.
The feed publishes one bar a minute. Rather than freeze the chart between two of them, the newest candle you see is a minute the tape has already delivered in full, revealed a step at a time over the following minute. Everything printed after it is held back until its turn.
Every price the candle shows is a price that traded inside that minute, and the candle finishes as exactly the bar it came from. What is ours is the order the prices come out in, because a bar records its open, high, low and close and not the path between them.
That order is what your fills are decided on. If the candle sweeps through your resting order, it fills, at the price you watched it reach. Nothing fills at a level the candle has not been to, and nothing is left resting after it has been through.
It costs you one extra minute of delay on top of the feed's own, which is the price of the screen and the fill being the same thing.
When the market is shut or the feed stops answering, the candle finishes its steps and then holds still. A chart that kept dancing on a dead market would be the lie, not the frozen one.