Yesterday morning, I took this photo in the Migros Gradelle store. Three identical Action labels, except for the price which differs between CHF 7.20, 6.30 and 5.10 for exactly the same batch of 6 × 400 g Longobardi crushed peeled tomatoes (https://www.migros.ch/fr/product/mo/58484).

The only explanation I could come up with was a possibly rather clever sales tactic: offer a limited quantity of units at an exceptionally low price to trigger immediate purchase; as soon as they disappear, only the packs at the standard promotional price remain available.

I'm still a little puzzled, and would like to know the exact reason behind this. Is it a deliberate tactic, a labelling problem or something else?

Thanks to the Migros team (and other members) if you can shed any light on this!