We intend to roll out the application of these limits gradually and impacted users will be notified in-app at least 60 days prior to the user limits being applied.
If you have not yet received a notification, you have at least 60 days until you will see any impact related to this change.
We on the dev team would rather stick with GitLab, but "Microsoft is icky so we need to pay four times as much for the same product" isn't very persuasive to the people holding the purse.
I will follow up if/when I can provide more specificity but it might be Monday before I have any more information.
Edit: the notifications will appear as global alerts directly under the Nav for all group owners.