<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=28126) </details> <!--IssueSummary end--> During our research for the cause of gitlab-ce#56861 we were confused by the values used for `notification_level` and `type`. They were named in a similar fashion which confuses readers of the code and e.g. makes reasoning about methods like https://gitlab.com/gitlab-org/gitlab-ce/blob/master/app/models/notification_recipient.rb#L48 more difficult. Even a slight change in wording might make sense here as suggested by @smcgivern : https://gitlab.com/gitlab-org/gitlab-ce/issues/60453#note_161660674 So we should evaluate new names for `type` and maybe refactor the code in `NotificationRecipient` so it is easier to find possible bugs.