V3 transaction policy for anti-pinning

The proposal suggests that a block should only be permitted to include a parent ephemeral anchor if it also contains the corresponding child spend. This is to ensure that the child spend transaction has at least two inputs. The rationale behind this rule is to standardize the amount of block space consumed by transactions, regardless of whether the payment to the miner was made within the blockchain system or outside of it (out-of-band). By doing so, the incentive for miners to accept out-of-band payments would be negated, as the block space used would be the same in either case.

The central question posed is whether such a soft fork, which would enforce these rules, would gain widespread consensus within the community. This is an important consideration since changes to consensus rules require broad agreement amongst network participants to ensure smooth adoption and continued security and functionality of the blockchain. The success of this proposed soft fork hinges on its acceptance by a majority of the network's stakeholders.