freedom to study the program's “source code,” and change it, so the program does your computing as you wish

Perhaps not a good idea, in general, to use a random PPA for such sprawling software as a browser. Auditability near zero even if it is open source.

This is a store we can’t audit, which contains software nobody can patch. If we can’t fix or modify software, open-source or not, it provides the same limitations as proprietary software.