Herokuapp request error

Please tell me who knows, this is a problem, I'm taking a course on js and there you need to make requests to the server and get information, yesterday everything was fine, I returned an object with data, everything worked, today I already have an error, here is the link: https://aviasales-api.herokuapp.com/cities

Or maybe it works on time? Is this my problem? Or there on the server? Please explain.

Still worked yesterday, and today connection errors and CORS. Wait for it to work? Yesterday, this link returned a huge cities object

Author: insolor, 2020-12-16