I don't remember, but I am getting old (and I've helped a few people).
You may want to execute the following query to see if environments, environment variables, and environment references exist in the recovered SSIS DB:
Select * From SSISDB.[catalog].environments
Select * From SSISDB.[catalog].environment_variables
Select * From SSISDB.[catalog].environment_references
You may also with to attempt a test deploy operation. It's possible to recover SSISDB improperly. If the deploy fails, the SSISDB database may have been restored, but not SSIS Catalog constituents. I blogged about this (for SSISDB 2016) at https://andyleonard.blog/2017/07/deploying-ssis-projects-to-a-restored-ssis-catalog-ssisdb/
Hope this helps,