I just discovered a weird bug in the online documentation for 8.1 when browsing via OS X 11.4, Safari 14.1.1
In this page: Core Modules
The icons for each of the core modules are also links to that modules description. Except for the perspective module. For that module it is still clickable, but doing so just brings the image up into an image viewer.
I also noted the same error on the Additional Modules page for Twilio, Serial and Secs.