Ubuntu has potentially serious privacy flaw

You're misreading this. X11 has a security flaw that allows any program to do malicious things, and this subverts security features in Snap. Not just Ubuntu is affected by this; all distros are and always have been, until a switch to Wayland or Mir is finally made.

The solution: don't depend on security features to protect you from malicious features. Do not run proprietary software, and prefer running only software which has been packaged and signed by the maintainer of the distro you use, if possible.