Watching this video, one could argue that, of course, these skills are rare, since some of them are no longer possible since the Gymnastics Code of Points has changed since them (making the distance between bars larger, devaluing certain skills,...), however, even at the time when those skills were possible, there were very rare.
On the subject of rare skills, the gymnastics world championships are less than 2 weeks away and while we got a glimpse of what we can expect at the Paris 2022 World Challenge Cup, perhaps the most awaited return is the one by the current uneven bars Olympic Champion, Nina Derwael, from Belgium. Nina, together with Becky Downie and Suni Lee is considered one of the best 3 bars workers on the planet, and currently, with Suni Lee taking a year off elite gymnastics and Becky Downie recovering from an injury, we can safely say that Nina is the best bar worker we will see competing at the 2022 world championships.
While all of those 3 gymnasts were remarkable not only for being able to do the hardest skills, combinations, and routines, they were also known for having different routines that they could perform depending on how they felt on the day or even the moment. On top of that, Nina is notorious for doing skills that nobody else is doing and even creating her own skills. We will have to wait for a few more days to find out what she has in store for us at this year's worlds.