I periodically need to add more than 10 people to MR and I do it manually. I add only one person at a time, through the search. Can I somehow add the whole team to the reviewers?
This does not seem to be supported, and could be added as a feature request, to be referenced in Epic: Merge request reviewers.
The alternative is to use quick actions, with GitLab 13.7+ (issue 241244)
But that presupposes you know the users' names beforehand.