Rex rabbits are more prone to sore hocks. Since their fur is shorter, the padding on the hock (i.e., heel of the foot) can get worn down/thin much easier than a rabbit with “normal” fur. Other things outside floorin can contribute to sore hock development, including a sedentary lifestyle, being overweight, and too long nails: https://wabbitwiki.com/wiki/Sore_hocks

Low pile wool, depending on age, wear, etc. can be more rough as opposed to soft (rough like a utility rug or something), and this can be a bit abrasive. That’s not saying your particular flooring is– just noting that some rugs/carpets are rougher than others and that can sometimes make a difference. Give the rug a good feel and make a judgement if it seems soft vs. rough on your bare skin.

Small pink bald spots is definitely not full-blown sore hocks, so it’s great that you notice them now. At this point, I’d just monitor and check them regularly to see if they get worse or not. Rabbits can form healthy calluses, and that is not concerning.

Are they on the heel or more along the other part of the foot?

I agree that since they are pink, it’s early on and not full on sores and is more likely a callus that you can keep monitoring.

The usual steps to take are to add extra soft fleece to her areas, especially areas where she tends to sit and rest a lot. Keeping the nails trimmed also helps, especially with the heel callus. You can also save up her fur when she molts, just in case you ever have to wrap her feet if she gets a full on sore.

A light pink spot is probably a callus. I agree with the others. Keep an eye on it and change up the flooring if necessary. You will want to watch out for redness and cracking, which is the start of it becoming sore. You don’t want it to become a full blown sore (open, bleeding, etc.).