This may not be your issue but I was getting error 400 malformed url when trying to link netlix account to Google assistant on my phone.
The solution was to make chrome my default browser on my phone. For android it was in settings:app:chrome:defaults
Hope this helps as this thread was locked:
Sorry for the late response, but I wanted to drop in here to help.
I understand that this can be confusing but I definitely wanted to stop by and see how I could help.
Just wanted to double check to see if you were still needing help on this? If so, what troubleshooting steps have you tried?
Please let me know.