What is the rest of her diet like?

A rabbit’s diet should be 90% hay, so in theory going without pellets for a few days shouldn’t be a big deal, unless pellets are what normally make up their whole diet and she doesn’t normally eat hay. I can’t believe she’s actually got thinner from not eating pellets for two days if the rest of her diet is correct.

If she does normally eat lots of hay, I would just make sure she had lots of hay, and maybe a bit of extra veg.

Rabbit food that’s a mix of dried fruit etc is generally not good for them, as they tend to pick out their favourite bits and don’t get a good balance. It’s also not ideal to suddenly swap a rabbits food, as it can be a shock for their sensitive digestive systems. So, as I said above, I would just keep her on a hay and extra veg diet until you can get her usual stuff in a few days. She probably doesn’t like the old one anymore because she’s not used to it.

The change in diet may have cause her digestive system to become upset, making her eat less.

Similar to human, taste buds change. So that’s a possibility. The more likely is she likes what she used to have more than what she had when she was younger. The food she had when she was younger was like new food territory, trying vanilla ice cream for the first time. Then you switched her to chocolate chip cookie dough which she realized was mucho better. Now due to the stores food supply, you’ve purchased vanilla ice cream again, so she’s not as enthused by it.

Make sure she’s still eating hay and veggies (if she’s old enough to). If she’s getting too hungry and malnourished before you can revert back to the old stuff, please feed her critical care so she does not starve and gets enough nutrients. Do not stick with the one you bought, because mixed pellets like the one you’ve described is not very healthy and has more sugar due to the dried fruit.

Unless you’re feeding tons of pellets normally, I can’t imagine she’d lose weight in two days w/o them.

Bunny’s tastes can change. Peanut used to love rocket but now isn’t interested. It happens.

With pellets, you need to introduce new ones slowly or you risk upsetting her stomach. You shouldn’t really be giving the muesli type ones anyway, they’re mostly junk.