glutathione now brand 250 mg Capsules NOW Foods Glutathione Skin Brightener,
Description
Retrieved January 10, 2021

That doesnt mean its wrong the chemistry is reasonable but it does mean the 100x more potent claims you see in promotional copy are essentially marketing language layered on top of plausible but unverified pharmacokinetic logic
Recently, the expression of the radial glia cell marker fatty acid binding protein 7 (FABP7) was found to be induced in activated astrocytes after cuprizone-induced acute demyelination whereas expression of this marker and the extent of astrogliosis was diminished after chronic demyelination (Kipp et al., 2011a)

Ruffle JK, Tinkler L, Emmett C, Ford AC, Nachev P, Aziz Q, et al

Most people do not "feel" an antioxidant working immediately

Some vitamin B12 supplements, such as liquid drops or sublingual tablets (tablets that dissolve under the tongue), may also need to be refrigerated to maintain their stability and effectiveness