Singer and actor IU promotes New Balance's apparel in this undated photo. Courtesy of E-Land

Political disputes about President Yoon Suk Yeol's impeachment over his botched martial law declaration have had unexpected impacts on brands endorsed by IU and other celebrities, who supported protests against him, as well as on companies related to his allies.

On Friday, IU's agency announced that the singer prepaid for food and hand warmers for her fans participating in a candlelight protest for Yoon's impeachment near the National Assembly in Yeouido, Seoul. After the announcement, Yoon's supporters began to encourage the boycott of companies who hired her as a spokesmodel, sharing the list of brands.

On the list were New Balance, HiteJinro and Woori Bank.

Although her endorsement agreements with water brand Jeju Samdasoo and Domino's Pizza have already ended, the names of the brands were also on the list shared by pro-Yoon consumers.

Since March, Samdasoo has been endorsed by trot singer Lim Young-woong, who was also embroiled in controversy after reportedly saying, "Why should I speak up? I'm not a politician," in response to an Instagram direct message questioning his silence on the martial law fiasco.

Some liberal consumers expressed their intent to boycott the mineral water brand because of Lim.

Domino's, which replaced its Korean spokesmodel with footballer Son Heung-min in May, denied any influence on its sales at the moment.

Woori Bank, on the other hand, is said to be dealing with complaints from anti-impeachment customers about its hiring of IU as a spokesmodel.

Companies endorsed by Girls' Generation's Yuri and members of K-pop girl group NewJeans have also become targets of Yoon's supporters, as the singers prepaid for meals for their fans participating in pro-impeachment rallies.

However, it remains to be seen whether the boycott will gain momentum, given that anti-Yoon consumers and fans of the singers have encouraged the purchase of products endorsed by celebrities supporting the protests calling for Yoon's impeachment.

Rep. Yoon Sang-hyun of the ruling People Power Party speaks before the press at the National Assembly in Seoul, Dec. 12. Yonhap

Among the companies facing boycotts over their connections to Yoon's allies is Purmil.

The dairy product maker's chairman is the father-in-law of Rep. Yoon Sang-hyun of the ruling People Power Party, who recommended that party members vote against the presidential impeachment motion.

The lawmaker, who divorced the late former President Chun Doo-hwan's oldest daughter in 2005, married Purmil Chairman Shin Jun-ho's oldest daughter in 2010.

"I will never buy the products of Purmil, (owned by) the family of Yoon Sang-hyun's wife, who defended insurrection," an internet user wrote online, sharing photos of the company's beverages.

Lotte GRS was also baffled after police alleged that a Lotteria store in Ansan, Gyeonggi Province, was the place where former and incumbent military intelligence commanders had met to discuss martial law operations two days before the president's declaration.

According to the hamburger franchise's operator, the store's owner is facing business setbacks, as internet users have left comments mentioning martial law on a website for restaurant reviews.