The potent poison created with the Poisoner feat isn't available as a common item in the Manage Inventory section of the digital character sheet.

The Poison, Basic (vial) poison is there, as well as the sample poisons from the DMG, but not the Poison, Potent (vial) you can create with this feat.

From TCOE: "With one hour of work using a poisoner’s kit and expending 50 gp worth of materials, you can create a number of doses of potent poison equal to your proficiency bonus. Once applied to a weapon or piece of ammunition, the poison retains its potency for 1 minute or until you hit with the weapon or ammunition. When a creature takes damage from the coated weapon or ammunition, that creature must succeed on a DC 14 Constitution saving throw or take 2d8 poison damage and become poisoned until the end of your next turn."

This is a good point. I have seen more passively mentioned items get full blown items (things like "this 1 locations of only this adventure has 1 vial of alchemist fire that deals extra damage" boom, Alchemist’s Doom).

This is made by a feat that any character can take.

now the basic poison is missing

Quote from becausewhynotfu >>

now the basic poison is missing

 
Its right here: poison, basic (vial)