Simkl keeps each anime season or part as an entry of its own, so finishing
one never led to the next in Next Up or Upcoming. The entry after a finished
one is now found through the anime mapping: the same TVDB show, its next part
or season.

- Upcoming lists the next season's first episode when Simkl's calendar dates
  it within the window, however long ago the last one was finished.
- Next Up offers it once it has aired, when the last season was finished or
  the new one began within JELLYFIN_NEXTUP_SEQUEL_DAYS (default 120).
- A season already on any of the user's Simkl lists is left alone.
- A season whose meta lists no episodes yet gets its first from the
  tracker's date, pictured as the meta pictures an episode without a still.