From sona pona, the Toki Pona wiki

The main sitelen pona glyph for yupekosi (yupekosi) is derived from the Latin letter Y, representing the joke of the word's spelling in sitelen Lasina. In November 2020, nimi Elemenopi designed a version based on the asymmetric form of Y that resembles its standard lower case version (y),[1] to distinguish it from the glyph for anu (anu), which has the same shape as an upright Y. Some fonts alternatively base the glyph on the alternate round-bowled form of Y like that used in cursive.

  1. nimi Elemenopi [u/ElemenopiTheSequel]. (30 November 2020). "A better version of the 1b glyphs". r/OffThePu. Reddit. Retrieved 28 December 2023. "[Key: black] = original, made by me".