The science
The chemistry of this gel is the chemistry of every gommage on the market, and it is well understood even if rarely printed on a tube. Carbomer, a cross-linked polyacrylic acid, thickens water when neutralised, here with aminomethyl propanol, into a clear anionic gel. Cetylpyridinium chloride is a cationic quaternary ammonium surfactant, better known as a mouthwash antiseptic. Anionic polymer and cationic surfactant can coexist in a carefully balanced formula, but shearing, dilution by sweat and the salts and lipids on the skin surface tip the balance and the two associate into an insoluble polyelectrolyte-surfactant complex, which appears as soft, grey, rolling pills. The same complex forms on an inert surface, which is why the crumbs are not evidence of exfoliation; the classic cosmetic-science demonstration is to rub the gel on glass.
What exfoliation occurs is mechanical. Hydrated silica is a fine amorphous mineral abrasive whose particles are softer and rounder than crushed nut shell; in a lubricating gel with thirty seconds of light circular friction it removes a fraction of the loosely attached outermost corneocytes, the same superficial effect a soft cloth or a gentle scrub produces, with the transient increase in skin brightness that follows any removal of light-scattering surface cells. Studies of physical exfoliation consistently show the benefit is limited to the outermost layer and short-lived, and that pressure and frequency, not the abrasive, determine irritation, which supports the brand's once-or-twice-weekly instruction.
The named actives cannot contribute under these conditions. L-ascorbic acid's percutaneous absorption and tyrosinase-inhibiting activity depend on a pH below about 3.5, a stabilised vehicle and prolonged contact, and it oxidises rapidly in plain water; a ninth-place listing in a neutralised, rinse-off gel satisfies none of those requirements. Glycolic acid's keratolytic action likewise requires a free-acid concentration of several percent at acidic pH over minutes to hours, whereas here it is a tenth-place, neutralised trace. Centella asiatica triterpenes have reasonable evidence for soothing and wound support in leave-on formulations at meaningful concentrations, which this rinse-off gel does not provide. What remains, once those conditions are applied, is a mild silica polish in a cationic peeling-gel base, with the label's actives present in name only.