As of macOS 10.14.5 (Mojave), according to Apple, all applications have to be certified by Apple (notarization). This process checks the applications for malware and, if successful, certifies the applications. Only these “certified” applications can be installed or started.
Although it will take a while until macOS 10.14.5 is available, we still have all 64 bit versions now notarized by Apple.
The updated versions can now be downloaded from the download page – and in the future, all new versions will be notarized.