Function apply_chain_and_block_specific_env_changes_for_chain 

pub fn apply_chain_and_block_specific_env_changes_for_chain<N, SPEC, BLOCK>(
    evm_env: &mut EvmEnv<SPEC, BLOCK>,
    block: &<N as Network>::BlockResponse,
    source_chain_id: u64,
    configs: NetworkConfigs,
)
where
    N: Network,
    SPEC: Into<SpecId> + Copy,
    BLOCK: FoundryBlock,

Applies block normalization for the provided source chain.

This keeps fork-specific header handling independent from an execution CHAINID override.