Access the following URL: https://commons.wikimedia.org/w/api.php?action=query&list=allimages&ailimit=max&continue=-||&aicontinue=20150312000632|Giannone_-_In_cui_contiensi_la_polizia_del_Regno_sotto_i_Normanni%2C_Svevi_ed_Angioini%2C_1770.djvu&aistart=20150312000000&aiend=20150312235959&aisort=timestamp&aidir=newer&aiprop=user|sha1|size|dimensions|mime|timestamp|comment|metadata&servedby=&requestid=1207435402
If not logged in as an administrator or bot, the API returns data normally, as expected. But if logged in as a Commons administrator or bot (and thus with the higher API limits), the script returns a 503 error every time, presumably due to an internal timeout being triggered for an internal component.
I believe this is related to but is not the same problem as T86611. Namely, that the API is not gracefully handling files with extremely large metadata (the first djvu it attempts to access above, for example, as 4.3 MB worth of data).