Websites transferred with Live Transfer might be redirected to domain.tld//cgi-sys/defaultwebpage.cgi during the time period before DNS changes are made or during propagation.
After an account is transferred using Transfer Tool with Live Transfer enabled (default on servers running version 90+), the account goes live on the destination server and proxies through Apache with ProxyPass to the destination server's hostname. See More: What is the Live Transfer Option?
The issue wherein the website displays the default web page can be caused by the destination server's hostname resolving a different IP address than the account is configured on the destination server.
Make sure that the destination server's hostname DNS IP address matches the account IP address. If the hostname resolves to an IPv6 address, that IPv6 address should be added as the shared IPv6 address on the destination server, and the account will need to be assigned to the IPv6 IP address.