From sona pona, the Toki Pona wiki

In her original messages and in the Toki Pona Dictionary, jan Sonja stated that "nobody knows how to pronounce the y".[1][2] In practice, it is often pronounced either as /j/ or [y ~ ɥ], or as a different random sound each time the word is used.[3]

  1. jan Sonja [@sonjalang]. (4 November 2019). [Message posted in the #toki-pona channel in the ma pona pi toki pona Discord server]. Discord. Retrieved 5 December 2023. "nobody knows how to pronounce the y".
  2. Cite error: Invalid <ref> tag; no text was provided for refs named ku392
  3. jan Ke Tami. "yupekosi". Retrieved 21 January 2024.