Checking a couple of points
Both 'shampoing' and 'shampooing' are formally accepted and used spellings, but the latter is being 'corrected' to the former here.
A 'bottle' of shampoo is mostly advertised and sold as 'un flacon' - ' j'ai fini le flacon ' is not accepted as correct though.
https://www.dictionnaire-academie.fr/article/A9S1514-A
https://www.carrefour.fr/p/shampoing-cheveux-normaux-carrefour-soft-3560070965137
https://www.e.leclerc/fp/dercos-psolution-shampooing-traitant-keratoreducteur-3337875787222