The meta tag output is filtered through ‘site_icon_meta_tags’. You could hook it and return an empty string if is_admin() is true.
The site icon is typically aggressively cached so I doubt you’d be gaining much, but it’s your site. You do you 🙂
We don’t cache admin side of the site so it’s hitting our servers. We confirmed from our hosting. Thank you for your reply. I will disable using your method.