Because eBay sees you as a 'new' seller since you have not sold in so long
You agreed to this when listing and you ticked you had 'read and understood'
If you fully completed sign up to Managed Payments and been verified to sell, your funds will be on hold for (usually) 30 days
It does not matter how long you have been on eBay, nor how much you sold years ago
The same policy applies to every single seller
Did you upload the tracking to the sale?
Worth actually reading what you ticked you had 'read' to avoid not knowing what you are agreeing to
