"upstream request timeout" 504 error when trying to import a large ticket

Hi! 

According to the Zendesk API documentation(https://developer.zendesk.com/api-reference/ticketing/tickets/ticket_comments/), I can only import ticket comments nested as an object inside a ticket. If the ticket has a lot of comments, the import takes a long time and the Zendesk returns the following error: 

Status: 504 
response: 
  date: "Fri, 14 Jul 2023 21:39:24 GMT" 
  content-type: "text/plain" 
  content-length: "24" 
  connection: "close" 
  x-zendesk-zorg: "yes" 
  x-request-id: "7e6..." 
  cf-cache-status: "DYNAMIC" 
  report-to: "{\
    "endpoints\":[{
      \"url\":\"https:\/\/a.nel.cloudflare.com\/report\/v3?s=IXB...\"
    }],
    \"group\":\"cf-nel\",
    \"max_age\":604800
  }" 
  nel: "{\"
    success_fraction\":0.01,\
    "report_to\":\"cf-nel\",
    \"max_age\":604800
  }" 
  set-cookie: "__cfruid=c21...; path=/; domain=.xxx.zendesk.com; HttpOnly;Secure; SameSite=None" 
  server: "cloudflare" cf-ray: "7e6...";
  Body: upstream request timeout

Did anybody experience the same issue? How can I import the ticket in this case?

Regards,

Ruslan