diff --git a/expression/integration_test.go b/expression/integration_test.go
index 2e0277ff0763f..ea12765fcf567 100644
--- a/expression/integration_test.go
+++ b/expression/integration_test.go
@@ -7910,3 +7910,16 @@ func TestAesDecryptionVecEvalWithZeroChunk(t *testing.T) {
 	tk.MustExec("insert into test values(aes_encrypt('a', 'x'), aes_encrypt('b', 'x'))")
 	tk.MustQuery("SELECT * FROM test WHERE CAST(AES_DECRYPT(name1, 'x') AS CHAR) = '00' AND CAST(AES_DECRYPT(name2, 'x') AS CHAR) = '1'").Check(testkit.Rows())
 }
+
+func TestIfFunctionWithNull(t *testing.T) {
+	// issue 43805
+	store := testkit.CreateMockStore(t)
+
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists ordres;")
+	tk.MustExec("CREATE TABLE orders (id bigint(20) unsigned NOT NULL ,account_id bigint(20) unsigned NOT NULL DEFAULT '0' ,loan bigint(20) unsigned NOT NULL DEFAULT '0' ,stage_num int(20) unsigned NOT NULL DEFAULT '0' ,apply_time bigint(20) unsigned NOT NULL DEFAULT '0' ,PRIMARY KEY (id) /*T![clustered_index] CLUSTERED */,KEY idx_orders_account_id (account_id),KEY idx_orders_apply_time (apply_time));")
+	tk.MustExec("insert into orders values (20, 210802010000721168, 20000 , 2 , 1682484268727), (22, 210802010000721168, 35100 , 4 , 1650885615002);")
+	tk.MustQuery("select min(if(apply_to_now_days <= 30,loan,null)) as min, max(if(apply_to_now_days <= 720,loan,null)) as max from (select loan, datediff(from_unixtime(unix_timestamp() + 18000), from_unixtime(apply_time/1000 + 18000)) as apply_to_now_days from orders) t1;").Sort().Check(
+		testkit.Rows("20000 35100"))
+}
diff --git a/planner/core/rule_aggregation_push_down.go b/planner/core/rule_aggregation_push_down.go
index c9326929b550f..2d3d0a607e9ce 100644
--- a/planner/core/rule_aggregation_push_down.go
+++ b/planner/core/rule_aggregation_push_down.go
@@ -538,6 +538,17 @@ func (a *aggregationPushDownSolver) aggPushDown(p LogicalPlan, opt *logicalOptim
 						newAggFuncsArgs = append(newAggFuncsArgs, newArgs)
 					}
 				}
+				for i, funcsArgs := range oldAggFuncsArgs {
+					for j := range funcsArgs {
+						if oldAggFuncsArgs[i][j].GetType().EvalType() != newAggFuncsArgs[i][j].GetType().EvalType() {
+							noSideEffects = false
+							break
+						}
+					}
+					if !noSideEffects {
+						break
+					}
+				}
 				if noSideEffects {
 					agg.GroupByItems = newGbyItems
 					for i, aggFunc := range agg.AggFuncs {