If used with the bank plugin - https://umod.org/plugins/bank the buttons remain on the player's screen when the bank container is closed.

I will check this, thanks for reporting.

Was also annoyed by that, adding this method fixed it for me.

private void OnPlayerLootEnd(PlayerLoot inventory)
{
BasePlayer player = inventory.GetComponent<BasePlayer>();
CuiHelper.DestroyUi(player, IdSortButton);
CuiHelper.DestroyUi(player, IdOrderButton);
}

Added the above suggestion, thanks.