The issue is fixed in version 1.4.9 – a hot-fix release is now available for upgrade on Mac App Store.
macOS always tries to terminate idle background services when it's under memory pressure, as the Core Shell's openssh service listening for network data, the system mistakenly considers it's in idle.
The solution is simple, just tell the system "I'm waiting for more remote data, not here idling at all, please don't kill me".
@HobaiRiku Thank you again for all your help 