The upgrade only affects BridgeHub. The upgrade contains a change to the Snowbridge Ethereum client to be much more cost efficient, resulting in a lower cost to run the bridge (estimated decrease from around $17,000 to $1,700 per month, which lowers the pressure on Treasury to run the bridge).

Release notes: https://github.com/polkadot-fellows/runtimes/releases/tag/v1.2.8
Enactment is set for 5 August.