As you can see, "open source" give s only half of those freedoms: to study code, it is not mandadory that you actually can modify it.
So, not all opens source software is free. Check out licence comparison and approvals page at Wikipedia.[3]
[1] https://www.fsf.org/ [2] https://www.gnu.org/philosophy/free-sw.en.html [3] https://en.wikipedia.org/wiki/Comparison_of_free_and_open-so...
At the same time, we see a MongoDB example: a software, which definitely is open source, but also definitely is non-free.
Free software: free for modification, expansion or forking. Possibly free for profit (BSD license)
Source Available: Source is available but under restrictions. Locked room source viewing under NDA to confirm there aren't vulnerabilities for example.
Source-available: You can view the source, perhaps freely, but can't modify or release your modifications.