There would have been a very good reason for closing the buyer's account.

Possibly a  scammer  ?

If the order's been cancelled, the buyer would be refunded.

BUT, was the item expensive, like your current listing  ?

Did the buyer really pay  or 'pretend' to pay ?

Was the payment  showing in your seller hub ?

Possible stolen credit card  payment ?

And as an aside, you haven't sold for a long time so eBay will see you as a new seller

Are you registered to sell and signed up for managed payments ?

https://www.ebay.com.au/help/selling/getting-paid/registering-seller?id=4792&srsltid=AfmBOopSNXkJ5fA...