You might be able to get away with it when the weight is light, but you won’t be able to get away with it when the weight gets heavy, and by that time, you’ll have accidentally ingrained a very counterproductive habit.
In the 5-step setup for the deadlift - stance, grip, shins, chest, pull/drag - this is typically a problem with step 4: squeezing your chest up to set your back in extension. When you lift your chest to set your back, you must start applying tension to the bar – you must start pulling on the bar even though you're not lifting it off the floor just yet. Treat the bar as an anchor against which you start to pull to help you set your back.
Here are 4 cues that you can use to help with this process: