I can’t confirm if it’s harmful or not, but when my bun shows any interest in the carpet we spray it with bitter apple spray and that keeps her away for a bit. Maybe if you put fleece blankets down over the carpet that could also help. I know my bun prefers fleece over carpet, and since fleece doesn’t have material fibres they can’t eat it, only bite holes through it if they really try.

If she is eating/swallowing a lot of carpet, that is concerning since it can block her up literally. There are some items to think about for carpet tearing reduction, in my opinion:

1) Allow options to dissuade from tearing up the carpet. Provide other things to be shredded and chewed, such as wood toys (bunny safe wood).
2) Is this carpet tearing behavior a sign of stress/discomfort? For this, I’d think about what rabbit food she’s eating (is there enough hay?), if her energy levels are normal, and other items. The observation that she’s pooping/peeing as normal is a good sign, but looking at every angle would be beneficial. Another angle could be looking at her relationship with your other rabbit — is this a potential source of stress somehow?.. and then also the garage environment — are there noises, smells, etc.. that may be stressful for her there?
3) If there are specific spots that seem most tempting, try covering them with a tile or something so it cannot be accessed.