You’re ignoring everything he wrote to you. While this article is written for when transferring websites to InfinityFree, it also applies to when transferring them OUT of InfinityFree.
You’re affected by DNS cache, and need to follow the advice in the “What can I do to see my website faster?” section.
The ?i=1 system is irrelevant, as your website no longer points to our servers. From the moment your nameservers and DNS records no longer point to us, nothing on our side can affect your website.
You can confirm that your site works fine by visiting it with a VPN or Tor, which by default uses a different connection and as such is not affected by DNS cache.