From what I've read and experienced, D'Addario started having their nylon filament manufactured in-house and ceased having it manufactured in Japan. They then had intonation and other problems with their nylon strings beginning in 2024 (or before) and throughout much of last year.
Fortunately, the new sets have extremely well intonated trebles and good basses. You can tell the new sets because the new trebles are clear unlike the previous trebles that have a cloudy look to them.
They show the nylon string making area in the D'Addario factory tour at 11:55
