@Kac1214 Did you ever find an answer for this?
I have just spent an hour researching the same thing. My best guess, as of 7/1/2022, is that this line is leftover from the old Form 8881.
The form's instructions states "Taxpayers, other than partnerships and S corporations, whose only source of these credits is from a partnership or S corporation, are not required to complete or file this form." Sole and C-corps are to claim it directly on Form 3800. So why are Line 6 and Line 10 singling out partnerships and S-corps if they are the only ones filing this form?
I am hoping the IRS comes out with some better guidance. Following the thread!
