Ergo Protocol Reference Client 4.0.21.1

It was considered in p2p layer that any block section is no more than some limit, namely, 2MB. While this is true for transactions (where limit can be changed by miners though and so exceed 2MB) and extension section (10 KB max), there is no check for UTXO set transformations proofs (most of the nodes generating and not downloading).

It was the case that one transaction made 5K UTXOs https://explorer.ergoplatform.com/en/transactions/4268e2bf73cb9b8e7e36ed04da8fe6759dd723f164b3ca2ff43c3e406c9c6995 . Then a light client (working in "digest" mode) caused problems for public nodes storing UTXO set, as they did not considered violation of the rule and so stuck in endless loop.

This release relaxing the issue by making full nodes not stuck if they some have a block section more than allowed block section size. In this case the node is still sending it. On client side, there is some relaxation of the limit. However, to protect light clients fully we need to introduce consensus-level checks for UTXO set transformation proofs in a next soft-fork, or miners can vote on raising cost of an output.

Also, too much of syncing traffic appeared in the logs. This release tries to cool down syncing.