Hello @ChenHungyi, and welcome to the Replit Ask community!
This is a problem with the TLS certificate, and not with your username changing.
When I go to the link with anygpt, it doesn’t work. However, switching over to http://, it works. This is because the TLS cert is required to establish a secure connection between the client and the server/page.
This has been known problem for a while, and multiple posts (like this or this).
I’d reccomend you to instead create a new ask post in #help with the topic of the TLS cert instead of the links being broken after the username change.
Hope this helps! 