When a player dashes in any given direction, there is an aura that envelops their character.
On the old client, the aura is stream-line and fits around the characters model in a sort of 'arrow' shape - whereas on the new client, this aura is larger and makes the dash much blurrier.
Here are comparisons:
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On the old client, the dash aura is much clearer and thinner:
Here, you can see the dash aura that envelops the player model is larger and blurrier:
https://i.gyazo.com/912628e043e22d8df80a6f1ecac5190c.mp4