Online account lists a different federal tax return amount than the printed version to mail. State return is fine. why?

Which is more?  Did you apply part of your federal refund to next year?  Which lines are different?  Maybe something changed after you printed it.  I would download a pdf to compare.  

Online version  lists $8,543.00 refund.  Below is a screen shot.   Refund Line 34 and 35a on printed form lists  $6,200.00.  Box 35a is not checked indicating Form 8888 was attached.    Line 36 does not list any amount should be applied to 2025 estimated tax. 

I suggest you print out the online version of the tax return and compare it to the printed version to see where there is a discrepancy and then investigate further.