ENGCOM-6552: Fix #22964 #26270

 - Merge Pull Request #26270 from marcoaacoliveira/magento2:2.4-develop
 - Merged commits:
   1. bb16e33
   2. d12ac21
   3. 32be472
   4. 6a19b12
   5. 6e80158
   6. 8ee89af
   7. c85410d

Author: magento-engcom-team

lib/internal/Magento/Framework/Stdlib/DateTime/Timezone.php

@@ -177,12 +177,12 @@ public function date($date = null, $locale = null, $useTimezone = true, $include
                 $timeType = $includeTime ? \IntlDateFormatter::SHORT : \IntlDateFormatter::NONE;
                 $formatter = new \IntlDateFormatter(
                     $locale,
-                    \IntlDateFormatter::SHORT,
+                    \IntlDateFormatter::MEDIUM,
                     $timeType,
                     new \DateTimeZone($timezone)
                 );
 
-                $date = $this->appendTimeIfNeeded($date, $includeTime);
+                $date = $this->appendTimeIfNeeded($date, $includeTime, $timezone, $locale);
                 $date = $formatter->parse($date) ?: (new \DateTime($date))->getTimestamp();
                 break;
         }
@@ -347,16 +347,44 @@ public function convertConfigTimeToUtc($date, $format = 'Y-m-d H:i:s')
     }
 
     /**
-     * Retrieve date with time
+     * Append time to DateTime
      *
      * @param string $date
-     * @param bool $includeTime
+     * @param boolean $includeTime
+     * @param string $timezone
+     * @param string $locale
      * @return string
+     * @throws LocalizedException
      */
-    private function appendTimeIfNeeded($date, $includeTime)
+    private function appendTimeIfNeeded($date, $includeTime, $timezone, $locale)
     {
         if ($includeTime && !preg_match('/\d{1}:\d{2}/', $date)) {
-            $date .= " 0:00am";
+
+            $formatterWithoutHour = new \IntlDateFormatter(
+                $locale,
+                \IntlDateFormatter::MEDIUM,
+                \IntlDateFormatter::NONE,
+                new \DateTimeZone($timezone)
+            );
+            $convertedDate = $formatterWithoutHour->parse($date);
+
+            if (!$convertedDate) {
+                throw new LocalizedException(
+                    new Phrase(
+                        'Could not append time to DateTime'
+                    )
+                );
+
+            }
+
+            $formatterWithHour = new \IntlDateFormatter(
+                $locale,
+                \IntlDateFormatter::MEDIUM,
+                \IntlDateFormatter::SHORT,
+                new \DateTimeZone($timezone)
+            );
+
+            $date = $formatterWithHour->format($convertedDate);
         }
         return $date;
     }

lib/internal/Magento/Framework/Stdlib/Test/Unit/DateTime/TimezoneTest.php

@@ -128,6 +128,18 @@ public function dateIncludeTimeDataProvider(): array
                 true, // include time
                 1495170060 // expected timestamp
             ],
+            'Parse greek d/m/y date without time' => [
+                '30/10/2021', // datetime
+                'el_GR', // locale
+                false, // include time
+                1635570000 // expected timestamp
+            ],
+            'Parse greek d/m/y date with time' => [
+                '30/10/2021, 12:01 π.μ.', // datetime
+                'el_GR', // locale
+                true, // include time
+                1635570060 // expected timestamp
+            ],
         ];
     }