reCAPTCHA Fails to Display or Validate in PMPro v3.3.2 with PayPal Gateway

[davidmutero]

Prerequisites

• I have searched for similar issues in both open and closed tickets and cannot find a duplicate.

Steps to reproduce the issue

1. Install and activate Paid Memberships Pro (v3.3.2) and the Pay by Check Add On.
2. Enable PayPal as the primary gateway and set the Pay by Check Add On as the secondary option.
3. Enable reCAPTCHA (v3 with updated keys) or reCAPTCHA (v2).
4. Attempt to complete a checkout with PayPal as the primary gateway and Pay by Check available as a secondary option.

Expected/actual behavior

When I follow these steps, I see:
• reCAPTCHA v3 fails with the error: “reCAPTCHA failed. (ReCAPTCHA not submitted.) Please try again.”
• reCAPTCHA v2 does not display on the front end at all.
• After completing payment and returning from PayPal, Cloudflare throws the following errors:
1. “Nonce security check failed.”
2. “The response parameter (token) has already been validated before. This means that the token was issued five minutes ago and is no longer valid, or it was already redeemed.”

Isolating the problem

• This bug happens with only Paid Memberships Pro plugin active
• This bug happens with a default WordPress theme active, or Memberlite
• I can reproduce this bug consistently using the steps above

WordPress Environment

``` WordPress Version: 6.6.2 PHP Version: 7.4.33 Paid Memberships Pro: v3.3.2 Pay by Check Add On v1.1.2 Server: Apache/2.4.57 (Ubuntu) reCAPTCHA v2 (v2 does not display). ```

[dparker1005]

This core PR may resolve this issue: strangerstudios/paid-memberships-pro#3225