Every time you capture an image or video in Photo Booth, those images are stored in a special file in the photo booth library stored inside the Pictures folder. You only need the Finder to be able to view the images of the photo booth. The PhotoBooth library is located inside the Pictures folder of the home folder. The small symbol at the bottom right will allow you to add the selected image to Photos and other sharing objectives.
Like iPhoto and Photos, there is a library of photo booths in the Pictures folder. Within the photo booth library, you can find all the images taken in an internal folder of images. I suspect that it is the file system lock introduced in BigSur that now prevents everyone from accessing their own photos. I want to automatically backup photos and videos from Photo Booth to Google Photos, but I don't know where they are stored.
As for automatic backup, there is no direct way to do it, since Photo Booth doesn't have many options for it. In case you don't use the application to manage your photos on your Mac, the photos won't be stored within the application package library, but you can easily find them with Finder in the Generic Pictures folder or anywhere else on your Mac system. If you have updated your Mac version to El Capitan or higher, the image folder will disappear, then you will have a hard time finding your photos. When you open the app, you'll be able to find all your photos and remember all the memories you've collected.
You can also use symbolic links to achieve this, by linking the Photo Booth app directory to the DropBox folder, or whatever. After you install the app and sign in to your Google Account, you can select the folders that Google Photos will automatically back up. You can also drag and drop individual images from the small Photo Booth image bar to the desktop or into a folder and save them individually outside of Photo Booth as a generic JPEG file. Remember that if you delete a photo from the “Masters” directory, you will no longer be able to access it in the Photos app.
If you want to make sure that there are no duplicate photos that can consume disk space, you should use the Similar Picture Finder module of PowerMyMac. After you finish the tour of the application and have done the initial setup, you are ready to import your photos and videos. If this is your first time using the Photos app, it will give you an overview of what your library looks like with all your imported photos and videos. In that sense, package files for Photo Booth are very similar to the original file library with the Photos application on the Mac, both accessible to users, but usually hidden from the average public through the file system.
However, with the method described below, you should be able to access the photos that were taken with the Photo Booth application just like any other normal file on your Mac. You'll get a quick introduction to some of the features and tools, and learn how to create concrete memories with the help of printable objects such as photo albums, calendars, and more.