You're probably thinking of VeraCrypt, which is a fork of TrueCrypt. I don't think BitLocker is related.
https://en.wikipedia.org/wiki/TrueCrypt#End_of_life_announce... - they are referring to this event, and the SourceForge page is still displaying the message along with a guide on how to enable BitLocker.
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https://en.wikipedia.org/wiki/TrueCrypt#End_of_life_announce... - they are referring to this event, and the SourceForge page is still displaying the message along with a guide on how to enable BitLocker.