I am viewing the answer by User 3.1415926535897932384626433832 to Why didn't Madara start his own plan when he was still young?. The entire answer is currently (revision number 2) within a spoiler block, but it is being displayed rather weirdly — perhaps due to the presence of a blockquote within the spoiler block?
Even without clicking on "Reveal spoiler", the last line of the answer is visible, despite the fact that the last line is placed inside the spoiler block (check the source formatting of the second revision to confirm).
After clicking on "Reveal spoiler", the line before the blockquote is revealed, whereas the blockquote is still not revealed, and a new "Reveal spoiler" button appears over the blockquoted part. At the same time, some portion of the blockquote is revealed, namely " --- Quoted from " and the full stop at the end of the sentence, a little distance away. The part between "from" and the full stop is a link, and it is hidden at this point.
After clicking on "Reveal spoiler" a second time, the entire answer is revealed properly.
Oddly enough, the spoiler formatting seems to work properly in the revision history of the answer, under the "Inline" as well as "Side-by-side" views.
For more weirdness, go to the link to the second revision. Here, the last line starts out unhidden, just as on the main answer under the question. However, clicking on "Reveal spoiler" just once opens the rest of the answer, unlike what happens on the main answer.
Considering the age of the question, it's probably fine in this case to fix the answer simply by editing out the spoilers completely; but, I thought it might be worth noting the bug with the spoiler formatting just in case it can be fixed.