New user form rejected because "passwords don't match"—but there's only one password field

I am trying to add a user to a blog of writings by or about my late father.  One of the articles is by my niece, but I cannot add her as a user.  The admin form only has one field for password, but when I click Add new user, I get Error: Passwords don’t match. Please enter the same password in both password fields.  Unfortunately, the form only has one password field!

Another QA says Current versions of WP allow creation of a user without creating a password but apparently, that is no longer the case.  5.8.1 outlines the empty field in red and puts an exclamation point in it, but doesn't say anything.

I can go into the database and create the user by SQL, but I don't know whether I would have to change other tables for DB integrity.

After I created the blog fifteen months ago, I was able to add an account for my father.  He is deceased, but I log in to that account when posting things he wrote.  I can't go back in time to see what the screen looked like fifteen months ago (actually, I could, if I were willing to spend ten minutes restoring a backup and ten more reversing it). But here's what it looks like today: