Which shiny variants can a Pokémon transferred from Pokémon Home have?

According to this french site :
https://www.pokebip.com/page/jeuxvideo/dossier_shasse/etoile-8g
If your pokemon originate from go/let's go/event, he will always have the Glistening black (square) effect.
If your pokemon originate from Gen 6/7 (XY and moon/sun), there is a 15/16 chance of having the sparkling white (star) effect (and then 1/16 chance of having the glistening (square) effect).
If your pokemon originate from previous game (rubis/saphire to black/white), there is a 7/8 chance of having the the sparkling white (star) effect (and then 1/8 chance of having the glistening (square) effect).

Considering that the odd in the wild for shield/sword, they are apparently reversed, with a 65521/65536 chances to get the glistening, and a mere 15/65536 chances to get the sparking.