It’s pretty well established that he was of African origin (likely from Mozambique, but debatable), and tall, brought to Japan by Jesuits. Before the 19th century, the Japanese diet consisted mostly of rice, fish and vegetables, someone of average European or African height would obviously stand out during the 15th and 16th centuries.
The problem is with just about everything else. Anyone claiming with absolute certainty Yasuke was made a samurai doesn’t know much about the subject matter, or they’re just lying for clout. There’s some unquestionable examples of Westerners being made samurai (William Addams stands out), which makes it even more obvious as to why Ubisoft chose Yasuke.