Google Sites Update of 2022: January - July
Google has extended the deadline for customers to migrate from classic Google Sites to new Google Sites.
Here is the new timeline:
Starting December 1, 2022 (previously June 1, 2022): You will no longer be able to edit any remaining classic Sites in your domain.
Starting January 1, 2023 (previously July 1, 2022): Classic Sites will no longer be viewable unless they are converted to new Google Sites.
This Google Site Migration Guide is also helpful when preparing the site for migration.