super heavy

Does anyone know why the second stage of starship flight test 7 caught on fire? also 10 and 25 mintues after the booster landed it caught on fire does any one know why? apparently the second stage burned up over turks and caicos is this ture?

SpaceX is planning Starship tankers but it seems to me that quite a lot of mass is going up and down for a sake of full reusability. Now, I am very interested in the subject, but my knowledge is lacking. With help of Claude AI :), I was thinking of a Super Heavy launching not a Starship tanker...