I generally disagree with what people think is "good faith" in debating. If I beat an instigator with a rational argument that is thought to be outside the consideration of the topic's scope(despite that a possible and rational interpretation can lead to that argument), it is the instigator's responsibility for not ruling out the consideration of such interpretation, and his own fault for not seeing this coming. If I am an instigator with a preset obviously favoring me and someone accepts it and loses obviously, it is the contender's responsibility regarding seeing how the preset really is. Debating a topic itself means that the scope should be defined as the topic itself and anything that could be interpreted from the topic itself should be valid.
In the same way, the scope of the vote is in the debating section for every debating webpage we have here. The comments should not be regarded unless they have been referenced in the argument section. We are really debating who has the better argument here, not who has the better faith or who is being convinced here, at least that is not decisive in terms of our voting structure on this very site. If you hold an argument, wrote an argument with significant quality, then decide that it is flawed so you concede, you should not lose because of it because then it is the equivalent of taking a position of "devil's advocate", and people do that all the time.
This is an issue albeit rare, but I have seen existing examples of it. Voters should generally not vote against someone just because they conceded in the comments, and if they conceded in the comments before the debate itself ends, they either should keep arguing a devil's advocate for the remaining rounds or just concede in a debate round in order to receive fair judgement. And if you really want to lose those points, which sounds extremely bizarre in my opinion, you are always free to open another debate.