Syncthing initially used MIT, then moved to GPLv3, and then to MPLv2. I'm not sure what the situation was when the first change happened, but when it comes to changing it again to MPL, the reasoning was that a less restrictive license would allow to publish the program in app stores with restrictive TOS (without asking the contributors to sign anything), and also allow to use the code in 3rd party proprietary software. Obviously, the last point is kind of the exact opposite of what this thread proposes
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