Honestly have you ever seen this version of the confederate flag ever used by actual Confederates during the Civil War?
I ask you specifically because of your bias as opposed to the bias of the Neo Confederates here that will just tell me about some book they once saw a picture in that no one can find or has ever heard of?
As far as I am concerned this version of the flag is not only historically inaccurate but is the very epitome of the versions of Confederate flags flown by Democrats, their minions of the Klu Klux Klan and other racists to ensure that Blacks in the south never achieved the civil right due to them under the 14th Amendment.
The square flag was used by the Army of Northern Virginia. The rectangular flag was used by many Confederate units in the Armies of Tennessee and the Trans Mississippi.
I cannot speak from personal experience of course, not having been involved in the war. However, I'm a big fan of Don Troiani, who is probably the preeminent artist specializing in painting the rebellion, and what look to me to be versions of this flag frequently appear in his work. Troiani is a fanatic for accuracy, so I have no reason to believe that this flag wasn't used by confederate regiments in one form or another.