As a Roblox user, it is somewhat confusing when you are removed from a group, but there is no notice sent to you by the group owner (or the person who removed you). When I am removed from a group, I generally notice a group missing, but I usually can’t figure out which one without stopping what I’m currently doing to check through every single group.
I think a notice such as the following, which appears in your notifications, would be useful to inform a person of their group removal:
Additionally, in the case of abuse, this would also allow for people who have been removed by an abuser to quickly rejoin the group.