Does anyone know what this circular thing is at 5:36 mark in the below video under the booster? It's like a piece which separated and keeps falling off. https:

Does anyone know what this circular thing is at 5:36 mark in the below video under the booster? It's like a piece which separated and keeps falling off. https://i.imgur.com/z6PH2Jw.png https://i.imgur.com/z6PH2Jw.png https://youtu.be/b28zbsnk-48?t=336 https://youtu.be/b28zbsnk-48?t=336