Hi,
In the French Wikisource, we noticed blue boxes appearing in empty pages on the PDF export:
- click on "PDF download" from https://fr.wikisource.org/wiki/Occupe-toi_d%E2%80%99Am%C3%A9lie_%21 (Ws-Export URL): two blue boxes appear on p. 175 (which is the first page in the "Acte deux" section of the table of contents)
- click on "PDF download" from https://fr.wikisource.org/wiki/On_purge_b%C3%A9b%C3%A9_%21 (Ws-Export URL): the same two blue boxes on p. 2 (which is the first page in the "On purge bébé" section).
In other places, I noticed even more blue boxes.