Selenium page_source not parsing content from body

I am trying to scrape a website with selenium, but I only get the following output in my terminal:
<html><head></head><body></body></html>

The following part is missing from the website:

<body>==$0
  <pre style="word-wrap: break-word; white-space: pre-wrap;"> 
  {"app":false,"service":[]}
  </pre>
</body>

This is my code snippet:

for i in pz:
    URL = '...={}'.format(i)
    print(URL)
    browser.execute_script("window.open('" + URL +"');")
    browser.implicitly_wait(5)
    for n in vc:
        URL2 = '...=L{1}'.format(i,n)
        print(URL2)
        time.sleep(2)
        browser.execute_script("window.open('" + URL2 +"');")
        browser.implicitly_wait(5)
        print(browser.page_source)

I tried xpath but couldnt find the element. I think js loads the content from somewhere else.