Formation of 2,4-Dichlorophenol by free chlorine mediated oxidation of Triclosan
I'm not sure if this qualifies as an answer since it's more of a guess. Catechols (1,2-dihydroxybenzene derivatives) can be oxidized to ortho-quinones. Applying that transformation here (chlorine in water is certainly oxidizing conditions) gives the oxonium of the ortho-quinone, which can be hydrolyzed to 2,4-DCP.