Hi Maxime!

> This seems like a trademark disaster to happen ...
> except that bitmask seems to have some kind of agreement with the VPN
> providers (see https://bitmask.net/en#providers), so this ‘rebranding’
> is ok I guess.

Yeah, the VPN provider configuration is done in source-code (i.e. before 
compilation). The official bitmask source will only come with VPN 
providers that LEAP (https://leap.se/) trusts and have understanding 
with. But I'm not sure how it deals with users from modifying 
source-code with custom VPN provider's branding. Since Guix distributes 
the official source-code, we should be fine.

> To make sure I got the terminology right:
> 
> ‘service provider’: gratis or paid provider for a virtual private network?

Yes.

> I don't see why one would tie software to a specific service provider?
> Besides that the software needs to support the network protocols used
> by the service providers of course.

Bitmask is tied to, not one but multiple-providers. Current tie-ups 
include RiseupVPN (https://riseup.net/en/vpn), CalyxVPN 
(https://calyx.net/), and LibraryVPN (https://libraryvpn.org/).

> I don't see _why_ bitmask would change the name of the application
> depending on the service provider, but whatever I guess. I mean,
> IceCat doesn't rename itself to ‘$ISP's Totally Secure Surfer’,
> e-mail clients don't rename theirselves to ‘$ISP MyMail’,
> depending on the Internet service provider.

I had the same thought. Usually VPN providers have their own client. But 
VPN providers who are non-profit/collective/etc, do not have 
dev-resources to develop and maintain app. So the providers I mentioned 
above, collaborate with bitmask. The bitmask project provides them the 
opportunity to re-brand the client as if it was developed by the them. 
This is white-labelling in a sense. :)

Regards,
RG.