[SpaghettiCthulu]

There's a line under the 6 for a reason. It tells you the correct orientation.

[suddenclarity]

I was looking for that but the line isn't visible on my computer unless I zoom in far. Maybe more obvious when doing the captcha for real and not looking at a compressed image.

[mattnewton]

Easy to miss in a timed operation that is threatening to lock you out of an account you might need to do your job.

[LinAGKar]

The line is barely visible due to the compression