Activity displays wrong names after migration

Summary

After migrating a project from another gitlab server to the SaaS version @gitlab.com using the export/import method, I have the following issues:

1. https://gitlab.com/camelotls/excalibur/ctp-authentication-service/activity displays only my name
2. https://gitlab.com/camelotls/excalibur/ctp-authentication-service/merge_requests displays that all requests were opened by me
3. https://gitlab.com/camelotls/excalibur/ctp-authentication-service/merge_requests/380 comments display my name as well

Steps to reproduce

Just visit the url's I shared in the description