Where: This change applies to Lightning Experience, Salesforce Classic, and all versions of the Salesforce app in all editions, except Database.com.
When: You can activate this update in Winter ’20. We’ll auto-activate this update on January 31, 2022. Orgs created in Winter ‘20 or later have ICU locale formats enabled by default.
How: Before activating this update in production, check with your package providers to make sure that all your installed packages are compatible with the ICU formats. Then evaluate the new locales’ impact to your organization. Use this SOQL query to find the locales in use in your org and a user count for each locale:
SELECT toLabel(LocaleSidKey) LocaleName, LocaleSidKey, Count(id) UserCount FROM User where IsActive=true GROUP BY LocaleSidKey
See the documentation for recommended areas of testing and details on the changes for each locale.
To activate this update, from Setup, enter Critical Updates in the Quick Find box, then select Critical Updates. For Enable ICU Locale Formats, click Review. Click Activate.