After migration of the users to Experience Cloud (through the User ID migration tool), the account should be linked to the original legacy Analytics username. As a result of this, the access to all the components, including segments/projects/calc. metrics shouldn't be changed.
In case you don't see to be the case, please reach out with the following details to firstname.lastname@example.org and we will help in resolving the issue.
Analytics company name
Analytics username (an example user seeing the issue)
Adobe ID/Federated ID details in Experience Cloud Admin Console