I’m from the US and so I can only speak to US law which I’m more familiar with and obligatory IANAL but… counterintuitively that is only _possibly_ infringement. More information would be needed to determine exactly if that is infringing.

Pinterest, like most sites hosting UGC is protected under 17 U.S.C. § 512(c) DMCA safe harbor laws.

The majority of pins on Pinterest are from the “pin-it button” a small snippet of JavaScript which content creators embed themselves on websites. Pinterest offers opt-out mechanisms but the majority of content creators see huge value in the additional traffic generated from Pinterest.