getting 429 response while sending request to api in laravel?

Question

Quite simple but confusing error,

In my IOS app which sends request to api gets 429 response code api is in laravel 5.8 and db is mysql

my api does this.... firstly it updates the records with latest information, secondly it appends the text file for my implementation and lastly it pushes response back to client end

this payload i recieve in my api

{
  "participationUID": "0EbaZtrVtbAmKodmR5jzVCu9c3wZYr",
  "locationData": [
    {
      "speed": "11",
      "longitude": "85.350918449668",
      "bearingAngle": "51.6760368347168",
      "timeStamp": "2021-03-07 03:51:08",
      "isSOSActive": "2",
      "latitude": "23.394939962300757",
      "accuracy": "4",
      "averageSpeedSoFar": "10",
      "distanceCoveredSoFar": "4.710738087463657"
    }]
}

this api hits every 2-3 seconds which is so frequently and i guess that might be the reason of getting 429 RESPONSECODE

but same api for android works fine

now firstly i am curious that why this is happening

1. is my backend code is slow
2. do IOS sending too many request while backend is processing
3. if 2nd option is yes why it is not happening in android and
4. what are the possible reason for this failure

also i have read about rate limiting in laravel which is throttle could it be better if increase it or will it solve my problem

 'api' => [
            // \Laravel\Sanctum\Http\Middleware\EnsureFrontendRequestsAreStateful::class,
            'throttle:api',
            \Illuminate\Routing\Middleware\SubstituteBindings::class,
        ],
```

so any help 
Thank you !!