[Repeal The 17th]

Originally it was “bold faced liar”.

[rellic]

That was always my understanding.
Bold, not Bald.

[Pythion.net]

I usually defer to Merriam Webster in such matters. They do their homework:

If you wanted a descriptor for such a lie in the 19th century, chances are you would have opted for barefaced (or in its slightly less common variant form, bare-faced). Lies (and, less frequently, liars) have been described as "barefaced" since at least the 1830s. The term was doing other jobs before it had that application, however. Since the late 16th century it's described those having the face uncovered, whether by being sans beard or sans mask. And in between, it developed the meaning "open, unconcealed," as in "barefaced impudence"—a descriptor for bold rudeness that paved the way for the "barefaced lie."
By the mid-20th century, it seems (though we can only speculate) that "barefaced lie" didn't sound awful enough, and the term bald-faced (less commonly, baldfaced) began to describe the lies and liars...
And then, in the late 20th century, the term bold-faced (less commonly, boldfaced) got into the game. Since the late 16th century (back when barefaced was first describing beardless folks), the word had meant "bold in manner or conduct," or "impudent." It was a word used to describe brazenly rude types. But in the second half of the 20th century the word began to modify lie, as well as liar, with a frequency that increased as the century wore on...
https://www.merriam-webster.com/words-at-play/is-that-lie-bald-faced-or-bold-faced-or-barefaced

[TigerHawk]

CONGRATS! Only 4 posts to a knowledgeable human being. Good to see.

[Mark17]

Originally it was “bold faced liar”.

I thought that was it too.