In Summer 21, "Require Verification When External Users Change Their Email Address" will be enforced. https://releasenotes.docs.salesforce.com/en-us/winter20/release-notes/rn_identity_confirm_email_address.htm

Does this only apply to external users who change their own email vs when a Sys Admin changes the email address on the User from Setup?

We don't currently allow our community users to change their own email address so I'm not sure if this will affect my users or not. I can't find this info anywhere. 

Thanks!