Recently got an issue that, users not able to view the latest Published Theme Image in their logins in Dynamics 365 CRM V9.X On-premises environment.

For illustration, added sample image in Theme record.

Actually below Image to be displayed in each and every user login.

But showing the Default Image of Dynamics 365.

Later identified that, this issue is because Enable high contrast option is Enabled Under Personal Option settings.

Uncheck the Enable high contrast option and click on OK.

Dynamics 365 CRM page will be refreshed automatically and Image will be shown.