api.call.transactionPaymentApi.queryInfo in the crawler code of Polkastats block explorer but I want to ask about the second parameter
len: is that the extrinsic lenght o what?
The encoded length of the extrinsic (ref).
Why is the len parameter required? The runtime doesn't know all the decoding context of the the encoded call (ref). So you can't just pass the encoded call and calculate the length in the runtime, because it won't be able to decode it properly.
Some references that helped me unravel this: