Please add the ability to pass simple variables to a custom block page.
For example:
Offending IP address/URL
Category of offending IP/URL
IP of host making the request
Username (if available) of the host making the request if available.
By appending variables to the end of the custom Block page redirect URL the block page can be dynamically updated to give the end user more details on why the request was blocked. It can able be used to programmatically interact with RMM/PSA tools.
Cisco Umbrella has had this this future for their custom block page redirects for several years.