When SSO is enabled for a portal the user sees a information box that reads "Please update your profile through your SSO provider."
The color of this information box can be interpreted as a warning / that something is wrong in the portal.
Red in user interface typically indicates a warning -> a different coloring would communicate better that this is nothing to worry about but rather just an information that user name and email cannot be changes in the user settings on the portal.
Change the color of the information box regarding SSO in the user settings on the portal to something that does not read as warning sign e.g., to a yellow box with an information icon.