Android Studio – Notification in Android Studio Not Coming on Time

I am currently developing an app on android studio using java where I want the user to be able to receive notifications from calendar events that they create. However, my notifications are not coming on time as they are either lagging or just not showing.

Here is my coding for the alarm receiver which sets up the notification:

public class AlarmReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        String event = intent.getStringExtra("event");
        String time = intent.getStringExtra("time");
        int notId = intent.getIntExtra("id", 0);
        Intent activityIntent = new Intent(context, CalendarActivity.class);
        PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, activityIntent, PendingIntent.FLAG_ONE_SHOT);

        String channelId = "channel_id";
        CharSequence name = "channel_name";
        String description = "description";
        NotificationChannel channel = new NotificationChannel(channelId, name, NotificationManager.IMPORTANCE_HIGH);
        channel.setDescription(description);
        NotificationManager notificationManager = context.getSystemService(NotificationManager.class);
        notificationManager.createNotificationChannel(channel);

        Notification notification = new NotificationCompat.Builder(context, channelId)
                .setSmallIcon(R.drawable.ic_launcher_foreground)
                .setSound(RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION))
                .setContentTitle(event)
                .setContentText(time)
                .setDeleteIntent(pendingIntent)
                .setGroup("Group_calendar_view")
                .build();
        NotificationManagerCompat notificationManagerCompat = NotificationManagerCompat.from(context);
        notificationManagerCompat.notify(notId,notification);
    }
}

Here is my CustomCalendarView Activity that sets up the alarm:

private void setAlarm(Calendar calendar, String event, String time, int RequestCode){
        Intent intent = new Intent(context.getApplicationContext(), AlarmReceiver.class);
        intent.putExtra("event",event);
        intent.putExtra("time",time);
        intent.putExtra("id",RequestCode);
        @SuppressLint("UnspecifiedImmutableFlag") PendingIntent pendingIntent = PendingIntent.getBroadcast(context,RequestCode,intent,PendingIntent.FLAG_ONE_SHOT);
        AlarmManager alarmManager = (AlarmManager)context.getApplicationContext().getSystemService(Context.ALARM_SERVICE);
        alarmManager.set(AlarmManager.RTC_WAKEUP,calendar.getTimeInMillis() ,pendingIntent);
    }

For example: When I set an alarm for 10:20 am, the notification either doesn’t pop up or pops up really late like at 10:22 am. Please help! Let me know if I need to provide any more information.