Best way to avoid Skull Merchant's drones in stealth mode

So in stealth mode, the drone does a rotational scan that is invisible. I've seen streamers run then crouch walk, etc to quickly get to the drone and disable it consistently without getting scanned. So I assume they know when it's safe to run in closer, and when it's not.

When might this be? I've read you can get an approximation by looking at the drone, but I don't understand what to look for.

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