Dropbox team is testing a new experimental build, which installs Dropbox to Program Files on Windows. This only happens when you run the installer manually, if previous Dropbox installation installed in the AppData folder and when the Dropbox auto-updates, then it will stay in the same folder. For 64-bit Windows, Dropbox will be installed into Program Files (x86).

Dropbox installed to Program Files

Dropbox tests New Installer for Windows with Helper for Updates Included

What do you say about this change of Dropbox Windows Client  installing to Program Files instead of AppData folder?

Dropbox Test Build adds File Identifiers and Long Path Support for files in Windows