I repurpose footage for use on social media... making one 20 second video out of re-used footage serves as a great way to spread the word on Instagram, Twitter and Tik Tok that I have a new full-length video coming out on YouTube. So I will include that as a YouTube short video. Might as well, it already exists.
That having been said, YouTube Shorts are tricky. They end up going on the Shorts Shelf and that is where you see the massive explosion of views. The problem is that there is a different, dedicated segment of viewers watching the shorts shelf. If these viewers see your video and subscribe to your channel you are collecting a large amount of viewers who's habits a vastly different than those who have been watching your regular, full-length videos. If this new influx of viewers does not enjoy your longer form content then that is a lot of empty subscribers to be picking up. And empty subscriptions can lead to poor video performance, which signals YouTube to give your videos less impressions.
It's not as dire as all this, but this is the worst case scenario. Make sure your Shorts content falls in line with your longer form content so that there is less of a jump between the two. Make sure the Shorts content is good for your already existing audience too. Just be aware you don't want to stray too far from your core content.