If you don't have a stable internet connection, that could be the reason - macOS sends a hash of every executable to Apple's servers before it is opened[0]. This caused a major issue at the end of 2020, when these servers stopped working and all macs stopped working unless disconnected from the internet[1].
macOS has also been updated so that syspolicyd bypasses VPNs and system firewalls like Little Snitch[2], so you can't easily block these connections now.
[0] https://www.reddit.com/r/netsec/comments/gp52pe/apple_is_tra...