Attempting to set a world title to "あア嗚呼あア嗚呼aaa" via the website results in it being set to "あ嗚呼あ嗚呼AAA". While I haven't confirmed it myself, I've heard this affects SDK uploads and avatars as well.

Tested with https://vrchat.com/home/world/wrld_cf31c30d-ef87-442b-8df4-f2f026d0c773