@DelacoursLangur Most of the reptiles at Pairi Daiza are rescues as they cooperate with a reptile rescue charity (Carapace). These might fit into that story also.
I have in any case never seen an Aldabra giant tortoise (or any other tortoise) in a zoo with pyramiding/shell malformation this bad (although I have seen individuals with some of it before).
To be honest, I wouldn't be surprised if this is their own doing. Especially because giant tortoises are not a species easily available to private keepers, so the chance of this many rescues is very slim. It's not the first time I hear about nutritional problems in Pairi Daiza saddly.