Turns out it’s the same as issue #5314. Hope it will be fixed soon - I’ve already encountered it twice in one book I’m working on.
When the line with the footnote move to the next page ebcause the footnote itself takes some space on the page, the footnote text remains on the original page, while the text where the footnote is is moved to the next page (and counted correctly there as 1).
A demo:
#set page(paper: "a6")
Lucas goes to school every day of the week. He has many subjects to go to each school day: English, art, science, mathematics, gym, and history. His mother packs a big backpack full of books and lunch for Lucas.
His first class is English, and he likes that teacher very much. His English teacher says that he is a good pupil, which Lucas knows means that she thinks he is a good student.
His next class is art. He draws on paper with crayons and pencils and sometimes uses a ruler. Lucas likes art. It is his favorite class.
His third class is science. This class is very hard for Lucas to figure out, but he gets to work with his classmates a lot, which he likes to do. His friend, Kyle, works with Lucas in science class, and they have fun.
Then Lucas gets his break for lunch. He sits with Kyle while he eats. The principal, or the headmaster as some call him, likes to walk around and talk to students#footnote[it's just the seargent] during lunch to check that they are behaving.
The next class is mathematics, which most of the students just call mathall#footnote[let it be]. Kyle has trouble getting a good grade in mathematics, but the teacher is very nice and helpful.
His fourth class is gym. It is just exercising.
History is his last class of the day. Lucas has a hard time staying awake. Many lessons are boring, and he is very tired after doing gym.
(Also opened as issue #8603)
