It specifically says she was dodging light speed though. And she did dodge light speed before:
Sike Cal, you really want this to happen geez. Here is narration stating "the space between her and Stella was freezing" during stella's dodges:
Along her line of sight, sword-like pillars of ice burst out along the ground as they crossed the space between her and Stella, as though she intended to freeze it all.
So she could see stella, the attack just wouldn't reach her in time, considering the space between "her and stella" was getting frozen, but stella was fine.
Narration states that she was dodging lightspeed. It wouldn't be "dodging lightspeed" if it weren't light speed.
Here is Stella dodging the glare from Mikoto despite not being outside of her field of vision:
Following her intuition, she kicked off the ground with all her might, propelling herself forward without any pre-preparation, just as the place she had previously been standing was frozen.
"This power is…!"
There was only one person here who could cause all the moisture in the air to freeze, creating that blooming flower of ice.
"The Icy Sneer's Satin Ice…tch!"
There, in the direction to which Stella had felt that shiver, was the stoically still Mikoto Tsuruya.
And her eyes of death were alight with a flame of green-white magic, unlike anything Stella had seen from her previously
In other words she dodged her field of vision completely in 1 jump after Mikoto was aiming at her.
Here is Stella again reacting by attacking despite Mikoto already having her in her field of vision:
Locking on to Stella, cut off from all escape routes, the light of Absolute Zero burst forth.
But Stella was not one to go down without a fight.
"Haaaa!"
Shrouding Laevateinn in her Empress Dress, she created a blade of fire that hewed the gaze of Hades aside.
ÒÇîSh, She repelled it with her sword! As expected, the Crimson Princess will not go down so easily!ÒÇì
She had already locked on to stella, yet stella had more than enough time to react to that by swinging her sword around and using fire magic too as well as scream.
Look your idea of how this is playing out keeps on getting proven wrong by the text over and over. Especially when the text outright says "she was dodging lightspeed".