I'm noticing that DomContentLoaded, Processing Time, and Load Time are all blank for Reddit withoutout uBO as well.

I'm going to make a mild suggestion that the author double-check their implementation logic. Is it possible that the ad-encumbered page isn't loading before it times out? Or is it possible that without ads the page is loading more content?

Even showing something like a comparison screenshot at the end might help in odd cases like this.