Alright here is what you can do (I do it too)
If you're on desktop there's an extension called BlockTube that lets you block anything. Lots of options that I'm not gonna go over but I use it to block garbage I don't wanna see including the shorts.
Edit: Now that shorts are a bigger part of youtube now, there is a setting at the bottom of the extension that blocks anything youtube tags as a short and the tab for shorts will be hidden as well.
Use the following advanced blocking function to block all videos one minute and less.
(video, objectType) => { // block all videos 60 seconds and under if (video.vidLength && video.vidLength <= 60) return true; return false; }