We recently followed the instructions to copy a Tier2 to Tier1 on page:
https://docs.microsoft.com/en-us/dynamics365/unified-operations/dev-itpro/database/dbmovement-scenario-exportuat#known-issues

The instructions do not specify where customizations should be applied to the target environment.

We have successfully applied customizations before the database restore, AND, after the database restore.

Please update the instructions with the appropriate time to apply customizations to the target environment.

Thank you :)