bpo3 mainnet preparation

[taratorio]

BPO3 is going to be scheduled on mainnet for some time in February.

This ticket is about adding BPO3 config to mainnet spec.

However, there are 2 additional sub-tasks expected to be delivered as part of BPO3:

• getBlobsV3 (should be ready by 1st week of January for devnet testing by ethPandaOps)
• a "max-blobs" input param for block building (check https://discord.com/channels/1359927674746835211/1428002540661899274/1428755341927125103)

[VBulikov]

taratorio added Imp1 as Importance

[taratorio]

@yperbasis fyi