We ran into an issue on 2021.1 with an integration which I wanted to share. Started getting a "request could not be understood by the server due to malformed syntax" error. They deprecated signature algorithm method HMAC-SHA1, which our integration was using in favor of HMAC-SHA256. Here's the SuiteAnswers link with the details and a code snippet: https://netsuite.custhelp.com/app/answers/detail/a_id/97854/