atomic.Time not being marshaled when calling json.Marshal

[BRUHItsABunny]

func TestTimeMarshal(t *testing.T) {
	type Test struct {
		Field1 time.Time
		Field2 *atomic.Time
	}

	obj := &Test{Field1: time.Now()}
	obj.Field2 = atomic.NewTime(obj.Field1)
	jsonBytes, err := json.Marshal(obj)
	if err != nil {
		t.Error(err)
	}

	tmpMap := make(map[string]interface{})
	err = json.Unmarshal(jsonBytes, &tmpMap)
	if err != nil {
		t.Error(err)
	}

	fmt.Println(fmt.Sprintf("JSON:\n%s", string(jsonBytes)))
	if tmpMap["Field1"] != tmpMap["Field2"] { // Field2 is not even a string as of right now
		t.Error("Marshaling not equal")
	}
}

Output:

=== RUN   TestTimeMarshal
JSON:
{"Field1":"2022-11-25T21:28:20.1068541+01:00","Field2":{}}
    utils_test.go:143: Marshaling not equal
--- FAIL: TestTimeMarshal (0.00s)

FAIL

As demonstrated, Go's std time.Time is able to marshal to JSON but atomic.Time doesn't do the same.
Was there a reason behind this?