I disagree with this for a number of reasons.
Let's get one of the obvious arguments against Void Manipulation out of the way: The fact that both Arc and Solar Light leave no traces behind of enemies either. There's actually explanations and mentions of this in the lore and when
used by NPCs they do the same thing.
As for the explanations in the lore.
https://www.ishtar-collective.net/cards/arc
This shows that Arc Light manipulates the forces that bind together complex matter.
https://www.ishtar-collective.net/cards/stormcaller
Here it is also mentioned that Arc Light affects matter.
https://www.ishtar-collective.net/cards/solar
Solar Light manipulates quanta, which means it's also
Quantum Manipulation.
In conclusion, the argument of Solar and Arc Light doing the same thing is a non-factor.
One thing I noticed is that the links in the OP don't actually disprove Void Light also being Void Manipulation.
https://www.ishtar-collective.net/cards/void
All it mentions is that beneath the world of matter and light lies the vacuum and that the Void Light is tied to vacuums. Void Light uses vacuums. And a vacuum is a space absent of matter, so if anything this points to Void Light using emptiness, nothingness.
https://www.ishtar-collective.net/items/warped-armlet
"It's still unwearable, but this armlet shivers with a greater power: atomic infinity,
utter absence, a dark and fractured mirror. You recognize this feeling now: residual Void Light."
I rest my case. The fact that it also mentions "atomic infinity" and "a dark and fractured mirror", both of which don't really mean anything, doesn't matter, because all elements have multiple functions and applications. Just because Void Light also manipulates gravity, doesn't mean it can't also be Void Manipulation.
https://www.ishtar-collective.net/records/the-accolade
"The sliding doors behind her opened with a whoosh, and a violet discus cut through the air above her, singing like a sword loosed from its sheath. Three of the creatures
dissolved into screaming Void as the disc of Light caromed down the length of the corridor."
This literally states they were turned into Void.
"Besides, Void based auto rifles or hand cannons simply shooting at already dead bodies don't disintegrate the enemy."
You can't do damage to corpses with weapons no matter what. This is clearly gameplay mechanics, unless it means that AP isn't actually a thing, considering kinetic weapons can't do anything to corpses either. And this is a revision for Void Light, not void weapons, anyway.
I really don't see why Void Light also having effects such as Status Effect Inducement and Gravity Manipulation contradicts it also being able to manipulate void. There's also Arc Light abilities that have Status Effect Inducement, but that doesn't mean Arc Light shouldn't have Electricity Manipulation, does it? Void Manipulation is simply on of the multiple uses of Void Light.