What is in /Applications is the program code (for want of a better phrase). It does not include data used by the application. I have always assumed (Apple doesn't say) that the size in General > Storage > Applications is an attempt to assess both program and data which I would expect to be larger than the program code.
To add confusion, I have apps which are larger in /Applications than they are in General > Storage > Applications. So I am not impressed by General > Storage > Applications.
I very rarely look in General > Storage > Applications. When I am concerned about disk space, I prefer to use apps like DaisyDisk which display sizes based mostly on the macOs folder structure.
Nevertheless you might want to explore how Identity is using your disk space. 84 GB (assuming it has some validity) suggests it is a bit out of control somewhere. You might want to contact the developer.
If you want to explore further yourself: run Identity, start Activity Monitor, select the app, double click to bring up a window dedicated to the app. Select "Open File and Ports". Explore the open files in Finder to determine if there any large folders being used by Identity and go from there.