Not sure if this counts as a bug or not so posting here.
spectacle commit ebee5b1d413eeba6a79f65160bc6cc1e543fdad1 changed how spectacle does placeholders in the filenames it saves as, from %thing to . When in a system update spectacle got updated my old placeholders (Screenshot_%Y-%M-%DT%H:%m:%S-%t) was entirely unchanged even though spectacle no longer uses/accepts the percents.
I feel as if this should be either auto-updated to the new format or at least some warning given of the change.
Related: the bug that caused this change was 476023 – Explain the sequential numbering filename template better (%Nd)