How to stop the screen from flashing?
WiFi Diagnostics Keyboard Shortcut in macOS Catalina

It looks like cmd+ctrl+option+shift+w triggers a WiFi Diagnostics session.

Browse to /Private/var/tmp and you'll see 300MB+ files titled WiFiDiagnostics_YYYY-MM-DD_IP4-address_Mac OS X_MacModelName.tgz

I can't find any official documentation on this, and I believe this is new for Catalina.