I would suggest that what you really learned was to ALWAYS "License" your contributions to any crowd-sourced project under CC-BY-SA, the #FSF #GPL or #AGPL, or some other #Creative_Commons or strong #Copyleft license.
Again: "License" your contributions - do not "ASSIGN" your copyright to any project. It's a common technique used by tricksters to steal your intellectual property for their own diabolical, ulterior motives like you just described
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