We have discussed the advantages and uses of Ethereum and Ethereum blockchain-based currencies throughout the previous chapters; let's now discuss some disadvantages of Ethereum-based tokens:

• Unstable: The Ethereum blockchain is still undergoing lot of changes; this also includes moving the consensus method from the PoW to the PoS system. 
• Dependability: The ERC20 tokens or any other tokens are based and built on top of Ethereum. This poses a threat, since Ethereum is itself undergoing frequent changes at most times.
• Hard forks: Being dependent on another blockchain means, due to hard forks, unforeseen issues can occur.
• Sovereignty: Since the tokens are based on Ethereum blockchain, there is no say in future development of these tokens. The decision of whether to choose ERC20 should be based on the application and use case.
• Support: Any improvements or requirements for support after the smart contract is published on the blockchain can only be done on the Ethereum blockchain and any changes/improvements suggested in the blockchain have to be approved by the whole Ethereum community.
• Ether as the main currency: Although with one can create their own currency, symbol and supply limit, ether is still the main currency used in the Ethereum blockchain, hence at all times Ether gets enriched for the efforts added by your token.