Maybe not a rollback, but Ethereum has proven it is malleable time and time again. As one example, compare the issuance of ether to Bitcoin. Eth's issuance is a dog's breakfast, indicative of changing opinions by those who call the shots... just like a central bank.
Bitcoin's issuance? Predictable and steady as a rock for 15 years.
Another example is replacing Proof-of-Work with Proof-of-Stake. A core part of how it works, important for censorship resistance and accessibility, and they removed it for something permissioned that makes censorship far easier.
Bitcoin? Still on PoW and never going to change. If you think it will change, you still don't understand Bitcoin. But never fear, there's already a PoS Bitcoin out there (that no one uses).