Gravity Forms: Error 400 (Bad Request)

Hello!

I’ve integrated Gravity Forms and Google Sheets with this plugin.
The records are inserted correctly in Google Sheets but upon activating debug, I receive two emails, one of them states “Failure” within the subject.

Inside, the main I can see regarding any error is:
“Your client has issued a malformed or illegal request. That’s all we know.

[response] => Array
(
[code] => 400
[message] => Bad Request
)
"

Here's the whole email in case anyone wants to take a look at it: https://pastebin.com/xy64MwiV

Any idea what may be going wrong?

Thanks a lot!