If it seems like she has successfully recovered from the spay with no issues (i.e. appetite and energy back to normal, no indicators of pain/discomfort, poop and pee output and quality normal), it probably isn’t spay-related. She actually reminds me a lot of my Fable, who at baseline is a rapid breather. Since there is no discharge, wheezing, or sneezing, I would recommend monitoring for now– she may just be a faster-paced rabbit. She is becoming an adult and growing into who she is and how her body is, so this may be a baseline for her.
I would also think about the environment. It is getting hot in some areas of the world, and faster breathing can be an indicator of being too hot.
Anxiety/hyper-vigilance could also be at play, potentially as a result of going through a spay (i.e. a stressful experience), so she is generally more alert now, rather than as relaxed. My Fable is a rabbit who is easily spooked/worried, so this is something I know impacts her breathing specifically.
The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.