I agree-most veggies that get frozen aren't really bunny veggies (peas, potatoes, asparagus etc) and usually need to be cooked to be edible-like Sarita said, they are limp afterwards

Freezing does not inherently change the food at all so in theory it's fine. Frozen fruit is just fine and I often give frozen fruit in the summer as a treat. Additionally I freeze papaya if I buy it so the buns can enjoy it for months.