What is the etymologically correct character for the Min-Nan words for meat (bah)?
The Austronesian hypothesis for the origin of Min Nan bah (as quoted on English Wiktionary, as of June 2020), comes from Deng Xiaohua's 1994 paper 〈南方漢語中的古南島語成分〉 (&quot;Proto-Austronesian in Southern Chinese Languages&quot;). I have attached an image here from a secondary source:

I see that the 16/17th century (Zhangzhou / Philippine) Hokkien-Spanish dictionaries are reported to have already had 肉 pronounced as bah (in their romanisation, bâ'). Hence this orthographic convention has had a relatively long time-depth compared to the other characters used for it.
What makes the connection harder is the lack of available cognates in other Min branches like Min Dong, Min Bei. If we believe Schuessler's link with 脢, which according to the 說文解字 means &quot;back meat&quot;, that wouldn't necessarily rule out an Austronesian connection.