Function block_blob_gas_limit 

pub(crate) const fn block_blob_gas_limit(
    optimism_jovian: bool,
    block_gas_limit: u64,
    max_blob_gas_per_block: u64,
) -> u64

Returns the block’s blob gas budget.

OP Jovian repurposes the block gas limit as the DA-footprint budget. Every other execution profile uses the active EIP-4844 limit.