@BTL512 Please review the following articles about this issue:
https://support.okta.com/help/s/article/Making-Azure-AD-as-an-identity-provider-returns-400-general-non-success-error?language=en_US
This can also be caused by issues with profile mappings, so ensure those are configured correctly as well: Map Azure Active Directory attributes to Okta attributes | Okta
If you are still seeing this issue, please open a Support case for 1:1 assistance