Hey,
Just wanted to make this post in case the Fedora Project was unaware of this issue.
It seems the Astronomy and Security Lab images are missing from the mirrors. There is also no entry in the sha256 file
Security Lab:
https://mirror.fcix.net/fedora-alt/releases/39/Labs/x86_64/iso/Fedora-Security-Live-x86_64-39-1.5.iso
SHA256 File:
https://mirror.fcix.net/fedora-alt/releases/39/Labs/x86_64/iso/Fedora-Labs-39-1.5-x86_64-CHECKSUM
Have a good day!
EDIT: I see the issue is known and tracked here: F39 release (#266) · Issues · fedora / Fedora Websites and Apps / Fedora Websites / fedora-websites-3.0 · GitLab