fix(datetime): max and min works with showDefaultButtons

core/src/components/datetime/datetime.tsx

@@ -564,10 +564,13 @@ export class Datetime implements ComponentInterface {
    * defaultParts if no active date is selected.
    */
   private getActivePartsWithFallback = () => {
-    const { activePartsClone, defaultParts } = this;
+    const { defaultParts } = this;
+    return this.getActivePart() ?? defaultParts;
+  };
 
-    const firstPart = Array.isArray(activePartsClone) ? activePartsClone[0] : activePartsClone;
-    return firstPart ?? defaultParts;
+  private getActivePart = () => {
+    const { activePartsClone } = this;
+    return Array.isArray(activePartsClone) ? activePartsClone[0] : activePartsClone;
   };
 
   private closeParentOverlay = () => {
@@ -1729,14 +1732,24 @@ export class Datetime implements ComponentInterface {
       return [];
     }
 
-    const valueIsDefined = this.value !== null && this.value !== undefined;
+    /**
+     * If a user has not selected a date,
+     * then we should show all times. If the
+     * user has selected a date (even if it has
+     * not been confirmed yet), we should apply
+     * the max and min restrictions so that the
+     * time picker shows values that are
+     * appropriate for the selected date.
+     */
+    const activePart = this.getActivePart();
+    const userHasSelectedDate = activePart !== undefined;
 
     const { hoursData, minutesData, dayPeriodData } = getTimeColumnsData(
       this.locale,
       this.workingParts,
       this.hourCycle,
-      valueIsDefined ? this.minParts : undefined,
-      valueIsDefined ? this.maxParts : undefined,
+      userHasSelectedDate ? this.minParts : undefined,
+      userHasSelectedDate ? this.maxParts : undefined,
       this.parsedHourValues,
       this.parsedMinuteValues
     );

core/src/components/datetime/test/minmax/datetime.e2e.ts

@@ -283,4 +283,52 @@ test.describe('datetime: minmax', () => {
       await expect(value!.includes('2022-10-10T08:00')).toBe(true);
     });
   });
+
+  test.describe('datetime: confirm button', () => {
+    test.beforeEach(({ skip }) => {
+      skip.rtl();
+    });
+    test('should apply max and min constraints even when user confirmation is required', async ({ page }) => {
+      test.info().annotations.push({
+        type: 'issue',
+        description: 'https://github.com/ionic-team/ionic-framework/issues/25073',
+      });
+
+      await page.setContent(`
+        <ion-datetime max="2022-01-10T15:30" show-default-buttons="true"></ion-datetime>
+
+        <script>
+          const mockToday = '2022-01-10T12:22';
+          Date = class extends Date {
+            constructor(...args) {
+              if (args.length === 0) {
+                super(mockToday)
+              } else {
+                super(...args);
+              }
+            }
+          }
+        </script>
+      `);
+      await page.waitForSelector('.datetime-ready');
+
+      // Select Jan 10, 2022
+      const maxDate = page.locator('ion-datetime .calendar-day[data-day="10"][data-month="1"][data-year="2022"]');
+      await maxDate.click();
+      await page.waitForChanges();
+
+      // Check to see that the hours have been filtered.
+      const ionPopoverDidPresent = await page.spyOnEvent('ionPopoverDidPresent');
+      const timeButton = page.locator('ion-datetime .time-body');
+      await timeButton.click();
+
+      await ionPopoverDidPresent.next();
+
+      const hours = page.locator(
+        'ion-popover ion-picker-column-internal:nth-child(1) .picker-item:not(.picker-item-empty)'
+      );
+
+      await expect(await hours.count()).toBe(4);
+    });
+  });
 });