You can also try solutions from the Official Addons Marketplace. We checked this module CAPTCHA Google reCAPTCHA PRO + anti Fake Accounts and it stops the Spam from Customer Account.
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You can also try solutions from the Official Addons Marketplace. We checked this module https://addons.prestashop.com/en/website-security-access/28831-captcha-google-recaptcha-pro-anti-fake-accounts.html and it stops the Spam from Customer Account.