Flag of the Eighth Route Army of the National Revolutionary Army (18th Group Army, NRA). Text on the side says 國民革命軍第十八集團軍. Based off https://inews.gtimg.com/newsapp_bt/0/13403539778/1000, https://new.qq.com/omn/20210413/20210413A00KYG00.html https://web.archive.org/web/20220109023936/https://new.qq.com/omn/20210413/20210413A00KYG00.html
Own work
TypeKnight03