The other one sold to them for what I can only assume is much lower than 18 - I think that sale and this one would balance each other out, and believe that updating this like it is done here is not the best idea.

The general consensus among moderators was that leaving this as it is is the best way to go here.

There are a few things in play here that make this a much more uncommon suggestion as it appears.

The sales situation itself is tricky already - as mentioned, 24 is statistically most likely the outlier here. It also does not help that the person that paid 18 dumped it for less later, usually an indicator that they paid too much/regretted their purchase.

The last thing that makes the situation here an odd one are buyers, which likely steered the sales to be on the high side here. In the sales we have here, they went up until it sold, and then they dropped back to <10. It should also be noted that it took like half a year to sell at 18.

Another thing that complicates matters here is that it was already accepted at 18 back when it was the only sale. Usually when single-sale raises dump to buyers, the suggestion ends up being rejected, but here it was accepted before it resold. Not taking either of those sales into account, it seems 24 would be really high considering how long it remained unsold at 18. This is further supported by the fact that even the person that paid 18 ended up selling it for less, meaning they likely did not even value it at 18.

Usually when we have situations like this, we just wait for more sales and leave the hat outdated, but since it was already updated based on that sale at 18, that is not an option here. Another alternative could then be to revert it, but I suppose that seeing how even the lowest dump was higher than it was before, it may not be that bad to leave it as it is. The average of all 3 sales as well as the middle value is pretty close to 18, I feel that reverting may be counterproductive, despite that being the typical course of action in a situation like this.

As an aside, when items are updated while still being in-date (so before they cross the 3 month threshold) is usually not done unless the change is significant and not selective. Had the new sale been the only sale, it would have been fine, but with the other sale here contradicting the premature change I would generally have been hesitant to update this. An additional reason why leaving this as it is seems to be the best call here.