I'm just trying to understand why people say Ethereum blockchain is decentralised.
Who decides when and how EIP1559 is implemented? When to implement Eth2, etc.
Isn't it just a small group of people controlling it?
Miners will be deciding whether EIP1559 will be implemented or not.
The implementation will be deciding based on the POW governance and in this case all of miners of ethereum in the world will able to vote whether they wanna support the implementation of EIP 1559 or not.
Don't mislead yourself. It's not small group of people controlling it.