Sorry, I believe this issue was already commented some time ago on this thread, but I don't remember exactly how it ended being the solution, neither the page where it was discussed.
I opened one of the free wheel spins received through email, but captcha is stucked and doesn't work: ERROR for site owner: invalid site key.
Closed and opened the link again few times, and the same message displays.

Can I still use this spin somehow, or is it lost due to this error?
I answered this one recently in our other thread. That's a reCaptcha error showing that it is an old cached version of the page.
I want to report that during the captcha phase in the freespin interface, sometimes there is the google recaptcha, sometimes another one I don't knwo the name.
When there is the google recapthca, a red message says "to site owner, invalid site key", the captcha is not functional. One or two refresh of the page usually loads the other non-google captcha that works.
You need to clear your cache. We have completely switched from using Google reCaptcha to hCaptcha so we no longer have a reCaptcha site key. You must be seeing an old cached version of the page rather than the current one.