I just want to say that this support website always has its pages updated recently with no sign of any actual content changes, so that part doesn't really mean anything and I think this text has been the same since it was published for PLA/BDSP's Home support.According to the official website, which was updated 2 days ago:
The moves a Pokémon can learn may differ between Pokémon Legends: Arceus, Pokémon Brilliant Diamond, Pokémon Shining Pearl, Pokémon Sword, Pokémon Shield, and other Pokémon games. For this reason, if a Pokémon is moved via Pokémon HOME to a game where it cannot learn its current move set, then its move set will be replaced with moves that it is able to learn in the target software.
So there may be some truth in that rumor.
This Spinda page on the sidebar was updated 30 minutes ago apparently despite nothing changing on that front.
https://support.pokemon.com/hc/en-us/articles/6425807283220-Why-can-t-I-withdraw-or-deposit-Spinda-into-Pokémon-Brilliant-Diamond-or-Pokémon-Shining-Pearl-