In March 2021, Mastercard changed its policies and prevents PayPal from offering Mastercard as a funding source within the PayPal wallet when depositing funds with lottery and wagering businesses.
If your PayPal deposit or deposit for Subscriptions has been declined, it could be because of this restriction.
To resolve this issue, you can choose to deposit funds with a debit or credit card stored within your online account, or you can add an alternative funding source within your PayPal wallet by visiting PayPal's website.