I'm also facing a similar issue reported to the team, due to holidays. It's still pending. Even though I have turned 'Paypal Account Optional' settings turned on. But still not able to accept the credit cards, only users with PayPal account can pay.
However, Under the Business setup>>Payment setup you can turn on the 'Payment processing:' to this 'You're going to process all payments, including credit and debit cards, through PayPal.'
Please do let me know if it's working cause for me this setting keeps on changing to previously set as default.