PayPal Checkout + Smart Buttons + Przelewy24 - There's a user with this email error

[AashikP]

Describe the bug

Cannot checkout as a guest user if you're using an email address of an existing account even though you have Allow customers to place orders without an account checked under WP Admin > WooCommerce > Settings > Accounts & Privacy

To reproduce

• Checkout as not logged in
• Provide the email address of an existing account
• Check out using some other than PayPal smart button (Przelewy24 or BLIK, haven't tested other countries' buttons or credit card)
• Pay
• Get back to the site to see the error that "there is a user with this email"
• Bank account charged, but no order created because of an error

(We're currently checking with user in 3235233-zen to see if allowing their customers to log-in during checkout helps)

Expected behavior

The behavior should be same as the built-in payment methods. If you're using PayPal balance, for example, you can process the order as a guest, even though you're using the email address that's already associated with a registered user. Eg:

Environment (please complete the following information):

• WordPress Version Latest
• WooCommerce Version Latest
• PayPal (Express) Checkout Plugin Version Latest
• Browser [e.g. chrome, safari] and Version Any
• Any other plugins installed N/A

Customer Reports

3235233-zd-woothemes

Slack: p1598949327165800-slack-lambda