A passerby walks in front of a Starbucks in Seoul, Tuesday. Yonhap

Kim Hye-joon, 30, doesn't go a single day without visiting Starbucks. But her daily routine may change following sharp criticism of the company over its controversial “Tank Day” promotion that briefly ran on Monday, the 46th anniversary of the May 18 Gwangju Uprising.

“I think this was extremely careless. I have no idea what they were thinking with the event and the wording,” Kim told The Korea Times on Wednesday. “I'm not about to smash my mug like some people on social media, but if there's a local cafe nearby, I'll just go there instead.”

Kim's sentiment reflects a broader backlash spreading among consumers and politicians, highlighting how a marketing blunder can ignite public fury in a country where the historical wounds around the 1980 uprising run deep.

The pro-democracy movement erupted in the southwestern city of Gwangju on May 18, 1980, when citizens stood up against the nationwide extension of martial law by the military junta led by Chun Doo-hwan, who would become president later that year. The crackdown left hundreds dead or missing, and it has since been recognized as a pivotal moment in Korea's long road to democratization.