This release contains RLP encoding of an additional field, baseFee in the block header. Geth had added this in the Clique consensus changes for EIP1559 but we had missed to add this in bor. The impact is mainly on downstream applications as the client libs might have a problem with the coinbase value.
Since there is a change in the block seal hash, this requires a hard fork at the Jaipur Block at block 22,770,000 for Mumbai Testnet.
Please note that this is applicable only for Mumbai Testnet. On Mainnet, when we rollout EIP1559, we will be setting the same number for both London and Jaipur blocks.