Hello,
I didn’t see any errors except legit in your request log on RapidAPI website.
If it works from RapidAPI playground but returns such errors for POST request in your scripts - I think this is due to malformed requests you are trying to submit. Don’t know reason as RapidAPI doesn’t show invalid requests in the log. But it’s either invalid request headers or malformed request body (e.g. you are sending POST data as json instead of url-encoded form). Hard to guess without seeing your code.