This can be for several reasons:
- You must have at least the role that can edit the “Company Branding” in Microsoft Entra ID is the Organizational Branding Administrator. This role is the minimum required to customize the company branding customization.
- You must have one of these licenses: Microsoft Entra ID P1 or P2, Microsoft 365 Business Standard, or SharePoint (Plan 1).
More info: https://learn.microsoft.com/en-us/entra/fundamentals/how-to-customize-branding
Hope this helps!
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