UHHHHHHHHHHHHHH
Teams must submit their initial competitive roster to Riot by October 15, 2022, alongside proof that players have the necessary work permits or visas to live in their hub city (Los Angeles, Berlin, or Seoul). But this is not a hard roster lock, and organizations can still make changes until February.
My guess is teams already submitted their rosters to Riot (without announcing), but the have a huge margin now for maybe getting others and then bench some of the submitted initially.
Example: Sentinels could've submitted shroud or SicK (they are under contract as far as i know) to fill the 6 man roster. Again, all this is in paper.