The Soulknife’s soulknife comes from their Psychic Blades subclass feature which states:

“Also at 3rd level, You can manifest your psionic power as shimmering blades of psychic energy. Whenever you take the Attack action, you can manifest a psychic blade from your free hand and make the attack with that blade. This magic blade is a simple melee weapon with the finesse and thrown properties.”

So would a soulknife disappear in an antimagic field or would it merely be a supressed magic weapon?

If its the later, would you be able to manifest it in an antimagic-field given that it uses psionic energy to manifest it even though it’s a magic weapon?

Would the other Soulknife class features that use the soulknife but aren’t described as magical still function, even if the soulknife is now a supressed magic weapon?

Also for the parameters of the question assume that this Sage Advice is correct: https://www.google.com/amp/s/www.sageadvice.eu/can-psionics-be-affected-by-anti-magic-like-the-anti-magic-cone-from-a-beholder/amp/