Unsubsribe chain head if it's a block over kaia fork

reward/staking_manager.go

@@ -466,7 +466,12 @@ func handleChainHeadEvent() {
 			}
 			if pset.Policy() == params.WeightedRandom {
 				// check and update if staking info is not valid before for the next update interval blocks
-				stakingInfo := GetStakingInfo(ev.Block.NumberU64() + pset.StakeUpdateInterval())
+				targetBlock := ev.Block.NumberU64() + pset.StakeUpdateInterval()
+				// After kaia fork, do not need to check staking info for the next update interval blocks.
+				if isKaiaForkEnabled(targetBlock) {
+					break
+				}
+				stakingInfo := GetStakingInfo(targetBlock)
 				if stakingInfo == nil {
 					logger.Error("unable to fetch staking info", "blockNum", ev.Block.NumberU64())
 				}