Change request.url in Scrapy to crawl a json file then return to the original request

I am scraping data from an url (product name, price, etc.) but there is a json file in the backend which I also want to scrape as it has relevant information. In a nutshell I want to change my request url to the json one and and then return to the original url so the crawling can continue.

1. Product url:https://www2.hm.com/hu_hu/productpage.0906822002.html
2. Related json url (this can be found in the Networks tab, and I store this in a variable named availability_url): https://www2.hm.com/hmwebservices/service/product/hu/availability/0906822.json

It would be very important to have the availability data in a variable before the actual yield as I have to return to the original url before checking the colors at the end of the code:

import scrapy
import re

class HMSpider(scrapy.Spider):
    name = 'hm'
    
    start_urls= ['https://www2.hm.com/hu_hu/learazas/noi/dresses.html']
    custom_settings = {'FEED_EXPORT_ENCODING': 'utf-8'}

    def parse(self, response):
        
        items = response.css('h3.item-heading  a::attr(href)').getall()
        for item in items:
            link = 'https://www2.hm.com' + item
            yield scrapy.Request(link, self.parse_item)


    def parse_item(self, response, request):
        page_source_data = response.xpath('//div[@class= "tealiumProductviewtag productview parbase"]//text()')[0].get()
        data = response.css('div.product.parbase script::text').get()
        base_product_code = re.findall("ancestorProductCode = '(.*)';",data)[0]
        detailed_product_code = re.findall("articleCode':'(.*)', 'baseProductCode",data)[0]
        current_price = int(re.findall(r'\d+',re.findall('product_list_price :  \["(.*?)\],', page_source_data)[0])[0])
        original_price = int(re.findall(r'\d+',re.findall('product_original_price : \[(.*?)\],', page_source_data)[0])[0])
        availability_url = 'https://www2.hm.com/hmwebservices/service/product/hu/availability/' + base_product_code +".json"
        info_url = "https://tags.tiqcdn.com/dle/hm/hdl/" + detailed_product_code +".json"

        if current_price != original_price:
            yield{
            'product_name': re.findall('(?<=  ).*$',response.css('section.name-price h1.primary.product-item-headline::text').get())[0],
            'vendor': 'H&M',
            'current_price': int(current_price),
            'original_price': int(original_price),
            'discount_percent': 100-round((current_price / original_price)*100),
            'colors': response.css('li.list-item a::attr(title)').getall(),
            'link': response.request.url,
            #rating
            #reviews
            }
            color_count = len(response.css('div.mini-slider li.list-item a::attr(href)').getall()) 
            if color_count > 1:
                additonal_colors = response.css('div.mini-slider li.list-item a::attr(href)').getall()
                color_index = 1
                for color in additonal_colors:
                    if color_index <= color_count:
                        link = 'https://www2.hm.com' + color
                        yield scrapy.Request(link, self.parse_item)
                        color_index += 1

So to sum up: I want to change the scraped url from https://www2.hm.com/hu_hu/productpage.0906822002.html to https://www2.hm.com/hmwebservices/service/product/hu/availability/0906822.json then return back to https://www2.hm.com/hu_hu/productpage.0906822002.html so my scraper can continue work.

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