This issue was addressed through improved state management. This issue is fixed in Safari 18.4, iOS 18.4 and iPadOS 18.4, macOS Sequoia 15.4. A download's origin may be incorrectly associated.
https://support.apple.com/en-us/122379
https://support.apple.com/en-us/122373
https://support.apple.com/en-us/122371
http://seclists.org/fulldisclosure/2025/Apr/8
http://seclists.org/fulldisclosure/2025/Apr/4