Whilst in the process of reviewing suggested edits, I mistakenly approved an edit that did not aim to improve the post.
Before I could do anything to fix, the link is gone and I fear this mistake could have bad consequence of rewarding users for harming otherwise good posts.
How can I revert this, in case I manage to track down the question?
You can't undo a review approval, but there's something you can do instead. Every post has a revision history, which you can get at by clicking the "edited time ago" link below the post. On this page, you can rollback to an older version of the post by clicking the "rollback" link on that version. This has the effect of undoing the edit (and any subsequent edits), but the person who suggested the edit still gets the +2 rep. You should explain why in the comment for your edit, because too much rollback-ing automatically raises a flag to alert moderators.
As bmdixon points out, just because you approved the edit doesn't mean the mistake is binding. Two reviewers need to approve a suggested edit. If the edit was that bad, presumably nobody else will approve it, so your mistake just means the suggested edit stays in the queue longer before being rejected. Even if somebody else makes the same mistake, the author of the post can now override the review result if they disagree. So it may be that the suggested edit never gets applied in the first place, and there's nothing to correct.
Automated review bans aren't a thing on this site. Stack Overflow has them, because there are a lot of users who "robo review" - clicking the buttons without thinking - just to get the badges. I'm proud to say we have a much better community here, so there's no need for such a system. Review bans are still possible for us, because the software supports them, but I don't think we've ever used them: there's simply no need. Even if we did use them, one mistaken review that you immediately try to fix wouldn't be a reason to ban you.
Looks like someone came to the rescue. As said by @bmdixon in comments, the suggested edits require two reviewers approval.
After going over links of suggested edits, I managed to grab the link of the faulty approved edit and noticed, that at the tine it was not awarded but was waiting for another review.
So if one reviewer approves and the other rejects, a third reviwer is needed to either approve or reject accordingly depending on the post.
Lesson learned: I have to be thorough in reviewing posts and prevent suggested edits that harm post or deviate intended meaning of post from being awarded to users, to ensure that quality is preserved on the site and high levels of reviewing are also maintained.
It tends out for now no one is getting banned for approving bad suggested edits this time but it is a wake up call :)
