According to the release notes for 1.17 (https://www.minecraft.net/en-us/article/caves--cliffs-part-i-out-today-bedrock), the command /whitelist has been renamed to /allowlist. However, if you actually start a dedicated server, you will see that /whitelist still works and /allowlist is not recognized as a valid command.
steps to reproduce:
start a server
type
allowlist list❌ the server responds with something like
Unknown command: allowlist. Please check that the command exists and that you have permission to use it.
type
whitelist list❌ the server responds with something like
###* {"command":"whitelist","result":[]}
*###even though this command should be removed in favor of allowlist
the correct command is /whitelist in the game, but in the server console is whitelist.
To add new players in the whitelist the right command is whitelist add "player name"