Is https://bugreport.apple.com/web/ restricted to developers?
Technically, you need a developer account and be signed into it to use that mechanism.

About Apple Bug Reporter
Apple Bug Reporter is a web-based tool that developers can use to
report issues with Apple software and services, request enhancements
to APIs and tools, and track the status of their feedback. To access
Apple Bug Reporter, sign in with the Apple ID associated with your
developer account.

(Emphasis mine)
The general public would use the public facing feedback page https://www.apple.com/feedback