Nobody here can fix this problem, we are buyers and sellers like you, nobody from eBay nor Paypal read here and the call center for eBay has been closed for weeks due to Coronavirus
Does it tell you why PayPal is blocking the payment?
When did you last use the account?
Does the seller accept PayPal?
Have you contacted the seller to let them know about the issue? (it might be on their end?)
Is it just the one seller or all payments you are trying to make?
Have you verified the account?
