Every piece of data on your computer that is owned by your user is available to any other app you run as your user. That's hardly unique to this data, and is a well known issue when it comes to personal data and the applications you run under the unix permissions model. That this is at least behind the "full disk access" control makes it more protected than something like all of the tax and accounting data your financial software is storing in your Documents or home folder (well, technically under macOS your Documents folder also has its own permission, but it's the same sort of thing where anything with permission to read from your Documents folder can read anything in there).

It's an eternal balancing act because every time Apple implements some new restriction in their OS that prevents apps from doing whatever they want, whenever they want, people get mad at them. But without those restrictions, the ever increasing amount of personal data that is stored on your computer is exposed to the ever increasing number of data slurping applications that you run.