Yes they three of the four are housed together. And there isn’t any bullying so perhaps this is normal for that one. As I said allare active and eating well
We have 4 leopard tortoises. Three are growing very well and the fourth isn’t. They allcame from the same breeder and don’t have worms. The fourth is much smaller but eats well and is active. Herpvet has no explanation
The tortoises don’t carry them in but you do on your pants legs! We recommend Bravecto which is a prescription topical or comfortis to control fleas on cats. Consult your veterinarian. Also you definitely do need to treat the environment