Unfortunately, Airbnb is using mostly AI in the review dispute process and it is not developed enough to be left alone without human intervention. It is a "toddler with a chainsaw" that results in predictable disastrous consequences.
Did she at anytime in the messages to you indicate she would leave a negative review if you didn't refund her? That is against Airbnb policies and the review should be removed based on that. Continue to escalate this with Airbnb:

Airbnb's Review Policy
https://www.airbnb.com/help/article/2673
For now, I am also advising all my Host clients to:
- Turn off Instant Book
- List on other platforms
- Consider a direct booking site
- Consider filing an Arbitration claim against Airbnb for not upholding their own written policies regarding review removals
Arbitration Claim
https://www.airbnb.com/help/article/2908#22