Most users have only a few pseuds, so the lack of pagination doesn't matter. This is mainly for the statistical outlier (orphan_account, 11k pseuds on beta).
How to test:
The pseud list of a user should not have pagination UI elements if the user has fewer than 25 pseuds (the ITEMS_PER_PAGE default).
https://test.archiveofourown.org/users/orphan_account/pseuds (note the missing trailing slash, this page is not blocked by nginx) should have pagination UI elements that work as expected.
Remove the nginx 404 block on https://archiveofourown.org/users/orphan_account/pseuds/.