Well it is enforced by the protocol on which all node agree and there needs to be a mechanism for syncing clocks across nodes (also defined by the protocol) but they exist, e.g. https://ieeexplore.ieee.org/document/8946264
Not 100% sure what ETH is using here but there is a mechanism.
If someone would want to fake timestamps, they would need to deviate from the protocol and would thus not be on chain.
Not 100% sure what ETH is using here but there is a mechanism.
If someone would want to fake timestamps, they would need to deviate from the protocol and would thus not be on chain.