Solution provided here: how do I get youtube shorts from youtube api data v3 does not cover "special" Shorts case.
There are some Shorts, ex. listed: here https://www.youtube.com/@SPARDALEDITING/shorts which if you click on them, since YT is working as SPA, change the URL to https://www.youtube.com/shorts/_LgGuQKEn4I, but if you go directly to that URL, it redirects to https://www.youtube.com/watch?v=_LgGuQKEn4I
Any ideas on how to verify such Shorts?
Except relying on the possibly false positives #shorts, I haven't found any way to solve your problem except using my StackOverflow answer on the question you mentioned. Indeed I show how to list the shorts of a given channel (notably _LgGuQKEn4I) cf https://yt.lemnoslife.com/channels?part=shorts&handle=SPARDALEDITING
So the only workaround to make sure whether or not a video is a short consists in getting the channel id from the video id and then list all the shorts of this channel (thanks to my answer) and if the video id, which you want to check whether or not is a short, is in this channel's shorts list then it's definitively a short.
