[Autocomplete] Fix label shrink issue when renderValue is used with empty array in multiple mode

packages/mui-material/src/Autocomplete/Autocomplete.js

@@ -588,23 +588,29 @@ const Autocomplete = React.forwardRef(function Autocomplete(inProps, ref) {
     ...getItemProps(params),
   });
 
-  if (renderTags && multiple && value.length > 0) {
-    startAdornment = renderTags(value, getCustomizedItemProps, ownerState);
+  if (multiple) {
+    if (value.length > 0) {
+      if (renderTags) {
+        startAdornment = renderTags(value, getCustomizedItemProps, ownerState);
+      } else if (renderValue) {
+        startAdornment = renderValue(value, getCustomizedItemProps, ownerState);
+      } else {
+        startAdornment = value.map((option, index) => {
+          const { key, ...customItemProps } = getCustomizedItemProps({ index });
+          return (
+            <Chip
+              key={key}
+              label={getOptionLabel(option)}
+              size={size}
+              {...customItemProps}
+              {...externalForwardedProps.slotProps.chip}
+            />
+          );
+        });
+      }
+    }
   } else if (renderValue && value) {
     startAdornment = renderValue(value, getCustomizedItemProps, ownerState);
-  } else if (multiple && value.length > 0) {
-    startAdornment = value.map((option, index) => {
-      const { key, ...customItemProps } = getCustomizedItemProps({ index });
-      return (
-        <Chip
-          key={key}
-          label={getOptionLabel(option)}
-          size={size}
-          {...customItemProps}
-          {...externalForwardedProps.slotProps.chip}
-        />
-      );
-    });
   }
 
   if (limitTags > -1 && Array.isArray(startAdornment)) {

packages/mui-material/src/Autocomplete/Autocomplete.test.js

@@ -3598,4 +3598,29 @@ describe('<Autocomplete />', () => {
       expect(textbox).toHaveFocus();
     });
   });
+
+  it('should not shrink the input label when value is an empty array in multiple mode using renderValue', () => {
+    const { getByTestId } = render(
+      <Autocomplete
+        multiple
+        value={[]}
+        options={['one', 'two', 'three']}
+        renderValue={(values, getItemProps) =>
+          values.map((option, index) => {
+            const { key, ...itemProps } = getItemProps({ index });
+            return <Chip key={key} label={option.title} {...itemProps} />;
+          })
+        }
+        renderInput={(params) => (
+          <TextField
+            {...params}
+            label="Fixed tag"
+            slotProps={{ inputLabel: { 'data-testid': 'label' } }}
+          />
+        )}
+      />,
+    );
+
+    expect(getByTestId('label')).to.have.attribute('data-shrink', 'false');
+  });
 });