Hello @CV1 

I see the opened tab is workspace tab. 

even though you set the favicon, it may not reflect for custom Workspace.

Try setting the logo from sys_ux_theme

refer the below support doc which explains the step by step process.

https://support.servicenow.com/kb?id=kb_article_view&sysparm_article=KB0964331

please mark the answer as helpful and correct based on the impact.

Kind Regards,

Ravi Chandra.