Here are three different reports regarding three different instances in Brazil. https://news.mongabay.com/2019/05/slave-labor-found-at-second-starbucks-certified-brazilian-coffee-farm/

https://news.mongabay.com/2018/09/slave-labor-found-at-starbucks-certified-brazil-coffee-plantation/

https://reporterbrasil.org.br/2023/11/starbucks-slave-and-child-labour-found-at-certified-coffee-farms-in-minas-gerais/

Here is one on the Guatemala incident. https://www.theguardian.com/business/2020/mar/01/children-work-for-pittance-to-pick-coffee-beans-used-by-starbucks-and-nespresso