The threshold score is 0.5, which is pretty lenient in terms of restriction. When rebuilding the captcha object class (which was done recently), my original plan was to put in a filter for customizing the threshold. That isn’t done, so there’s not yet a mechanism to customize it.
Ordinarily, I would go ahead and push that forward and tell you how to patch it with what future code is planned. But in this case, that has yet to be determined so I can’t give you what that is going to look like (also, lowering the threshold below 0.5 is likely to make the captcha considerably less effective). So I’ll have to give you information on “hard coding” the value (which I ordinarily would avoid), and give you the caveat that (1) this WILL be overwritten when you update the plugin, and (2) there will be a mechanism in the future to adjust this to a custom value (likely a filter), and that change will be noted in the change log in the readme.txt file.
In the file /includes/class-wp-members-captcha.php, if you scroll down to almost the very end, you’ll see the logic test for the captcha score:
$recaptcha->score >= 0.5
reCAPTCHA v3 scoring is between 0 and 1, with 0 being a bot, 1 being a human. Lowering the value loosens things up a bit.
