See attached screenshots, pretty much says it all.
Note that this is from clicking on the actual notification in the upper right corner; the Graceful Server Reboot in the left hand navigation works fine.
Hey there! I'm not able to reproduce this on a test server. I updated the kernel through SSH to trigger that reboot notification, but clicking on either the top or bottom link in the WHM interface takes me to the reboot page. I confirmed the URL is the same - https://x.x.x.x:2087/cpsess0414688750/scripts/graceful_reboot_landing?suggest=1
I was testing this in AlmaLinux, but if you could let me know your operating system I can check this again on a different platform.