Short answer: vitamin B12 may help lingering visual effects mainly when a B12 deficiency is involved, which is more likely after nitrous oxide use. I cannot verify outcomes for any one person.
Nitrous oxide is reported to inactivate vitamin B12, and low or functionally inactive B12 can present with neurological and psychiatric symptoms, sometimes including hallucinations. In such cases, stopping nitrous oxide and restoring B12 status has been associated with improvement in some reports.
For HPPD after psychedelics without nitrous oxide, evidence that B12 resolves symptoms is limited. Still, ruling out a B12 deficiency can be worthwhile. If you are concerned, consider asking a clinician about testing B12, MMA, and homocysteine, and discuss whether supplementation makes sense for you.
For a short overview of the topic, see this explanation on B12 and lingering hallucinations: B12 and persistent perceptual symptoms. Stay safe.