External domains can frame your Visualforce pages or surveys in an inline frame (iframe) only when you add them to an allowlist. To let a trusted site load a Visualforce page or survey in an iframe, add its domain in Session Settings and set the iframe type to Visualforce Pages. Domains that aren't on the allowlist can't frame your pages.
Where: This change applies to the Salesforce mobile app for iOS and Android.
How: From Setup, in the Quick Find box, enter Session Settings,
and then select Session Settings. In the Trusted Domains for Inline Frames section, click
Add Domain, enter the domain, and select the Visualforce
Pages iframe type. Acceptable domain formats are example.com,
https://example.com, and *.example.com.