How to say “Politely admit mistake” professionally

Level 1: I've reviewed the recent data compilation and noticed an oversight in my contribution to the Q3 report. I'm actively working to correct this discrepancy and will provide an updated version by end of day today.

Level 2: Upon re-evaluating the Q3 report data, it appears there was an area where my input could have been more thoroughly cross-referenced. I'm prioritizing the necessary adjustments to ensure alignment with our expected outcomes, which I will share shortly.

Level 3: Regarding the Q3 data, it seems I applied the exact parameters from the initial, unrevised brief rather than the subsequent, uncirculated update. I'll endeavor to acquire the definitive 'final' version for future contributions, assuming one eventually materializes.

Level 4: There was an error in my data entry for the Q3 report, which I have now identified and corrected. In the future, clearer version control or a final sign-off process would prevent such isolated incidents.

Level 5: My bad. Your problem now.

Level 1: Thank you for bringing this to our attention. We've identified the discrepancy you mentioned regarding the project deliverable. We are implementing the necessary adjustments and will provide an updated timeline for resolution shortly.

Level 2: We appreciate your keen observation regarding the recent deliverable. It appears there was a misunderstanding of a specific requirement during the initial phase. We are now aligning our approach to fully meet your expectations.

Level 3: Indeed, the 'minor deviation' from the original SOW's unquantified 'flexibility clause' has been noted. We're now proceeding with the 're-scoping' that seems to occur with every iteration, at no additional cost to our internal sanity.

Level 4: We acknowledge the error in the deliverable. Our team is actively correcting it. To prevent future misunderstandings, we will require more explicit sign-off on all subsequent phase requirements.

Level 5: You get what you pay for.

Level 1: Thanks for flagging that. You're right, I overlooked that detail in the initial review. I'll correct it on my end and send over the updated version shortly.

Level 2: I appreciate you pointing that out. It seems there was a slight divergence from the intended approach on my part. I'll integrate your feedback to align with our collective objective and finalize this.

Level 3: Ah, yes, the 'detail' that wasn't explicitly outlined in the initial task brief I received. Consider it 'rectified' according to the unspoken expectations that evidently shift daily.

Level 4: You're correct, I made an error there. I'll rectify it. For future tasks, let's ensure all critical requirements are documented and mutually agreed upon upfront to avoid such discrepancies.

Level 5: And?