Who does not belong in the united Nation?

As of now, the Holy See (Vatican City) and Palestine are non-member observer states in the United Nations, meaning they have limited participation but do not hold full member status. Additionally, countries like Taiwan are not recognized as UN members due to political reasons and the One-China policy, despite having a functioning government. Thus, any entity or territory that does not meet the criteria for full membership or lacks recognition by key member states may be considered as not belonging to the UN.