The gradual roll out of this change started with a blog post[0] and included in-app notifications for the owners of impacted groups on GitLab.com.
If the group owner did not log in during the in-app notification period, they were then emailed (the email you received today) notifying that the group was impacted.
[0] - https://about.gitlab.com/blog/2022/03/24/efficient-free-tier...
“On display? I eventually had to go down to the cellar to find them.”
“That’s the display department.”
“With a flashlight.”
“Ah, well, the lights had probably gone.”
“So had the stairs.”
“But look, you found the notice, didn’t you?”
“Yes,” said Arthur, “yes I did. It was on display in the bottom of a locked filing cabinet stuck in a disused lavatory with a sign on the door saying ‘Beware of the Leopard.”