BungeeCord has a new feature which they call inject_commands. This basically implements tab complete like we know from spigot. If enabled, it reveils every possible command of luckperms to players. Players normally have no permission to use these commands, but still can see them. This should not be possible if it laks the correct permission. Normally players have no permissions at all. Better yet: a player should not be aware that a server runs luckperms or not.

Could this be prevented?

Luckperms 4.3.38 for BungeeCord

The LuckPerms tab complete handler already checks for the corresponding commands permissions before providing completions to players.

https://github.com/lucko/LuckPerms/blob/fc69002c86941981d54a59386d611fda29e639ed/common/src/main/java/me/lucko/luckperms/common/command/CommandManager.java#L242

Better yet: a player should not be aware that a server runs luckperms or not.

They will always see at the very least the first command part of the command tab completion for /lpb and equivalent, as players are able to use the base LuckPerms command with no arguments without being given any specific permission.

Ah I see. No sub commands are coming through.
Imho even the base command is not necessary but maybe I'm a bit to strict on these things
Thanks for letting me know.