User issues with Google reCAPTCHA

We have one client and a subset of their users who struggle with Google's reCAPTCHA. They report issues of not being able to solve the challenges.

Our issue is we don't have that problem. Even when purposefully failing the challenge by selecting an incorrect tile or not selecting enough tiles, the challenge either submits correctly or informs us that we're missing a selection.

The captcha is applied to a payment form, and we don't want to remove it as this client has had issues with bots in the past.

Is there any other bot-thwarting system or practice that might solve this problem?

We used to utilize honeypots in the past but as autofill has become better, we've had to phase that out.