Google Places API not returning all restaurants inside bounds (not even close)

Hi everybody, I'm using Google Places Javascript API in order to return all restaurants and food related places inside a small rectangular bound, issue is I'm getting 10-14 places inside area but there should be much more, according to docs I can get up to 60 results split in three batches of 20 results, so why am I getting so few results?

I this because the clients SDK are limited, should I use the backend SDK instead? My objective is to retrieve all restaurants in a city, I want to do this by splitting the map in a grid and searching each cell, but sadly I'm not getting accurate results at all...

This is my code:

search()
    {
        const self = this;

        var bounds = new google.maps.LatLngBounds(
            new google.maps.LatLng(36.720054, -4.405126),
            new google.maps.LatLng(36.721490, -4.404268)
        );

        self.placesService = new google.maps.places.PlacesService(self.map);
        

        var request = { bounds: bounds, types: ['restaurant', 'bakery', 'cafe', 'food', 'meal_takeaway', 'bar', 'meal_delivery'] };

        self.placesService.search(request, self.placesCallback);
        
    },

placesCallback(results, status, pagination)
    {
        const self = this;
        // process the resutls  
        if (status == google.maps.places.PlacesServiceStatus.OK)
        {      
            //console.log(results);
            self.results = results;

        }
    },