Is the SAMLRequest parameter superfluous when not signing requests?

Help
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1

We are encountering an issue with our IdP login redirect (sp initiated SSO).
While https://domain.com/path/to/endpoint provides a login prompt, the URL being generated by Auth0, https://domain.com/path/to/endpoint?SAMLRequest=TOKEN&RelayState=BLAH, causes the endpoint to throw an ambiguous error.

Is there a way to drop the parameters from the URL? We are not using signed requests.

thanks!