I was checking the code in the link @JammyDodger shared, and I just had a guess.
The limit is calculated dividing 100 by the count of categories that has some group in the field of moderation.
Since the moderator category is a thing we want to expand the use, we already linked groups with categories even the group is empty.
By doing so, the limit ended up being 1, even though we are far from showing 100 on the about page.
I guess this explain the situation I noticed.