The dispute was a "Significantly different to how it was described" claim.
I posted the item back to the seller.
I uploaded the tracking and label details as requested by Paypal.
I received an email from Paypal saying that the seller had 3 days to respond, and that the response would be shared with me.
Five days later, I receive an email from Paypal saying,
"We reviewed the claim(s) you filed on 28 July 2020. Unfortunately, we had to deny your claim(s). The decision was made because we did not receive a response from you with supporting details for the case."
I am very anxious to contact Support to find out what went wrong.