add some context comment

zetaclient/chains/evm/signer/gas.go

@@ -97,6 +97,10 @@ func gasFromCCTX(cctx *types.CrossChainTx, logger zerolog.Logger) (Gas, error) {
 			Str("cctx.forced_priority_fee", gasPrice.String()).
 			Msg("gasPrice is less than priorityFee, setting priorityFee = gasPrice")
 
+		// this should in theory never happen, but this reported bug might be a cause: https://github.com/zeta-chain/node/issues/2954
+		// in this case we lower the priorityFee to the gasFeecCap to ensure the transaction is valid
+		// the only potential issue is the transaction might not cover the baseFee
+		// the gas stability pool mechanism help to mitigate this issue
 		priorityFee = big.NewInt(0).Set(gasPrice)
 	}