How is MIN_EPOCHS_FOR_BLOB_SIDECARS_REQUESTS guaranteed?

[zhiqiangxu]

Quoted from here:

Clients MUST support requesting sidecars since minimum_request_epoch, where minimum_request_epoch = max(finalized_epoch, current_epoch - MIN_EPOCHS_FOR_BLOB_SIDECARS_REQUESTS, DENEB_FORK_EPOCH).

What happens if clients don't support requesting sidecars at all for saving bandwidth, is there any kind of punishment in this case?

[dapplion]

There's no punishment currently. Syncing clients will downscore and eventually disconnect from the non-serving clients. We rely on honest behaviour to uphold this invariant AFAIK.