The SN11 is the last vehicle of the second version of the prototype. The next vehicle will be called SN15 and will have many more important modifications to bring it closer to the final version. Coming back to SN11. This time, the engineers failed to successfully put it on the Boca Chica site.
The entire test took place in bad weather. You can’t see much in the movies because the region is hazy. Probably SN11 exploded as a result of anomalies during the landing maneuver. It is quite possible that there are leaks in the fuel tanks.
Source: GeekWeek.pl/SpaceX / Photo. NASASpaceFlight