With the Salesforce Spring ’23 release, Enhanced Domain will automatically be turned on by default for all your Salesforce organizations unless specifically opted out.
Please consult our troubleshooting article to learn more about the potential impacts of enabling Enhanced Domain.
How to opt out of the automatic deployment of Enhanced Domains
To opt out of the automatic deployment of enhanced domains, take these steps in each org before the org gets Spring ’23.
Step 1: From Setup, in the Quick Find Box, enter “My Domain”, then select My Domain.
Step 2: If you see "Step 3: Deploy Your New Domain," your new domains with enhanced domains are ready for deployment. To access the option to opt out of the auto-deployment in Spring ’23, click Cancel New Domain.
Step 3: In the Routing section of the My Domain Setup page, deselect Automatically deploy enhanced domains with Spring ’23, and save your changes. That setting applies only when the org gets the Spring ’23 release. It isn’t available when enhanced domains are enabled or if a change to your My Domain is pending deployment.
You can also consult Salesforce's official documentation to get more information about this option.