diff --git a/zetaclient/chains/evm/observer/observer.go b/zetaclient/chains/evm/observer/observer.go
index 8823b13c47..64281bebcb 100644
--- a/zetaclient/chains/evm/observer/observer.go
+++ b/zetaclient/chains/evm/observer/observer.go
@@ -95,7 +95,12 @@ func NewObserver(
 		evmJSONRPC:                    evmJSONRPC,
 		outboundConfirmedReceipts:     make(map[string]*ethtypes.Receipt),
 		outboundConfirmedTransactions: make(map[string]*ethtypes.Transaction),
-		priorityFeeConfig:             priorityFeeConfig{},
+		priorityFeeConfig: priorityFeeConfig{
+			// temporary disable EIP-1559
+			// https://github.com/zeta-chain/node/issues/3221
+			supported: false,
+			checked:   true,
+		},
 	}
 
 	// load last block scanned
diff --git a/zetaclient/chains/evm/observer/observer_gas_test.go b/zetaclient/chains/evm/observer/observer_gas_test.go
index da64d32972..e0dcd16416 100644
--- a/zetaclient/chains/evm/observer/observer_gas_test.go
+++ b/zetaclient/chains/evm/observer/observer_gas_test.go
@@ -38,11 +38,11 @@ func TestPostGasPrice(t *testing.T) {
 		observer, _ := MockEVMObserver(t, chain, ethRPC, nil, zetacoreClient, nil, blockNumber, chainParam)
 
 		// Given empty baseFee from RPC
-		ethRPC.On("HeaderByNumber", anything, anything).Return(&ethtypes.Header{BaseFee: nil}, nil)
+		ethRPC.On("HeaderByNumber", anything, anything).Return(&ethtypes.Header{BaseFee: nil}, nil).Maybe()
 
 		// Given gasPrice and priorityFee from RPC
 		ethRPC.On("SuggestGasPrice", anything).Return(big.NewInt(3*gwei), nil)
-		ethRPC.On("SuggestGasTipCap", anything).Return(big.NewInt(0), nil)
+		ethRPC.On("SuggestGasTipCap", anything).Return(big.NewInt(0), nil).Maybe()
 
 		// Given mock collector for zetacore call
 		// PostVoteGasPrice(ctx, chain, gasPrice, priorityFee, blockNum)
@@ -69,6 +69,8 @@ func TestPostGasPrice(t *testing.T) {
 	})
 
 	t.Run("Post EIP-1559 supports priorityFee", func(t *testing.T) {
+		t.Skipf("Skipped due to https://github.com/zeta-chain/node/issues/3221")
+
 		// ARRANGE
 		// Given ETH rpc mock
 		ethRPC := mocks.NewEVMRPCClient(t)