English: This is a further reconstructed flag of the Lanfang Republic in an attempt to better cite a flag rather than sourced from Reddit. The description used to reconstruct this flag is taken from Research done by the famous Hakka historian Luo Xianglin in his detailed biography on Luo Fangbo and the Lanfang Republic, "Research on the Republic Founded by Luo Fangbo and others in West Borneo", in 1961. His research led to the revival and interest in Luo Fangbo and the Lanfang Republic in China. His work constitutes the groundwork and majority of research done from then on, including the Wikipedia page of Luo Fangbo. His flag rendition closely follows that of the book "Hakka People: The Jews of the Orient" by Kao Chung Xi. However, Kao Chung Xi's work, did not mention the color of the Characters leaving much ambiguity. Luo Xianglin's research noted that the characters are red, stating as follows:

"...The flag of the Republic of Lanfang is a yellow rectangular flag with a yellow field and red lettering, inscribed with the words ‘The Great General System of Lanfang’ in large letters."

Zh:

「兰芳共和国的国旗为黄色长方形旗帜，黄地红字，上书“兰芳大总制”几个大字」

Please keep in mind this is indeed a reconstruction. Other than this, there is very little else to go off of, like dimension, etc. The previous flag has even flimsier records, and the text (which reads just 'Hakka') is quite incorrect, even with the sources we have.