It’s difficult to get details on this, probably because it’s a private residence.
One report claimed the burglars smashed into safes hidden in the bedroom. Of course it would be nice to know the make and model of the safes and what “smash” really means.
Several articles state there is 24/7 security, and some say the burglars were in the house for 50 minutes.
This suggests incompetent security and/or inside information.
With the Ecclestones’ money and (presumably) influence we might never know much about this.