Flamingdragon is right, and unfortunately I’ve had that happen myself to a rainbow male 🙁 The plastic can react with the clear coat finish of a piece. I’m sure not all pieces would react, and not all bubble wrap could cause a reaction, but why take chances?
On a related note, some have reported that paper can get stuck to these pieces as well. Fluctuating humidity is likely a big contributor to that.
Forever seeking: Blackwatch the raffle Old Warrior, Jennifer Miller's pieces, and GB Baby unis!