Next time you setup for your deadlift, take a look at where the bar is in relation to your shins. That bar should be right up against your legs, both for conventional and sumo.
When the bar is closer to you, you are better able to use your hamstrings, glutes, and lats to help lift the weight. This start position allows you to keep your shoulders over the bar and your hips in the right position to begin lifting the weight. When the bar is too far out front, you can’t use your leverage properly without first having to redirect the bar back towards your body. And that redirection is usually done by your low back.
Keep that bar CLOSE!