the leviathan scan has no relation to the attosecond feat, because it's completely different instances.
https://imgur.com/a/iqUBMel
you guys are just speculating at this point if superman was restraining his speed when he was saving the woman. Not saying he couldn't go MFTL, but he wasn't during that instance. you can use other showings to prove his speed, just not that one.
superman narrative in the scan suggest he wasn't holding back. He said "I know my top speed, I know the distance. I'm close, but this is math, I won't make it." at no point did the writer mention he was restraining his speed. he was accelerating yes from supersonic to hypersonic and then beyond. so from mach 1 to maybe somewhere like 10.
This attosecond showing makes no sense whatsoever anyway. the writer is suggesting superman was only moving hypersonic but can extend his arm out in attosecond? The bullet is only traveling 830 feet persecond. In femtosecond or attosecond basis the bullet would be standing still in air, not reaching to the woman's temple. This is just poor writing all together. might as well throw that feat away.