by 3 grandson's. been working on it since confinement.
I used to be able to do it, easily, until maybe my mid-40's but haven't tried one since, nor will I.
anyway... never having successfully landed a backflip, from any of my 3 grandson's.... we just went outside and all 3 did so, on their first attempt. Right now they are very cocky, chest bumping, sending selfies.