Bitcoin's decentralized and permissionless nature is its biggest advantage but also its biggest weakness: it's too easy to create fake nodes.
'fake nodes' is not a big weakness to the BTC network, i don't think the idea of fake nodes can be a problem if they don't control 51% of the network's hashrate, if they don't control 51% of the hashrate, then whatever malicious transaction would be detected by other nodes and would be dropped because there are far more good nodes than malicious ones.
But I believe that a permissioned and decentralized network is also possible. For a node to enter the network, a 51% approval of validators already approved in the network is required.
If permission is required, then i don't think it is decentralized anymore, it is now somehow centralized and people can now be censored, BTC works the way it does because it is censorship resistant and permissionless, and the pow algorithm ensures optimum security of the network, the worry is only if a 51% attack happens, and it is impossible.