Is there an error in the logic of requests to the site and working with a proxy?

Question

Python

There is a site similarweb.com . You need to go through the domains in the file and return the content from the site (delivered in the form of json. I did this, if the code is 200, then everything is fine, just return the data. In other cases, make up to 20 attempts with other proxies. Starts parsing from the site banki.ru And every other time it sends None (without knocking out an error), but sometimes it sends the correct data from the site. Tell me, is there a logical error in the
code
?