Just a quick update. Even though the problem persists, this is my temporary workaround (hopefully it works):
On the Auto Return Page Template (optional customizations) under PayPal Options I added this to the Auto Return Page Template Header (first line):
<meta name="robots" content="noindex, nofollow">
I also added this to my robots.txt file (not sure it works, since the address is a query, I tried to set up a redirect on NGinx but I wasn’t successful and it seems to be quite complex to code a redirect properly, so only requests to that specific page without coming from a purchase/subscription are redirected):
And, on top of that, just in case, I also made a request for google to not feature that url on search results, and I’ll do the same with Bing and Yandex.
Is it possible to include a redirect for when someone (human or robot) visits
/?s2member_paypal_return=1 without a query originated from a purchase or subscription on a future plugin update?
I have a strong feeling that my SEO plugin is partially culprit from what happens (RankMath) and I also reached out to them about the issue.
Thanks again for everything!