iOS has been this way for a couple versions, and I can't imagine how it ever passed testing.

Animations that block use input are the sort of stupidity that becomes evil in its own regard. There was even a calculator but with this. This is a massive failure at the management level; somebody actually codes these things, but that it's not caught anywhere before shipping shows that the wrong people are in charge.

It's the sin of losing the user input.

Don't make your user repeat something twice :)

I do not have this experience on the screen lock screen (on Ubuntu 18.04 at least) — just typing a password will put the full password into the box once the animation is gone.

I do not log-in frequently enough to remember how it behaves on log-in (even my laptop has ~90 days of uptime).

FWIW, moving away from GNOME 2.x to either Unity or GNOME 3 was a hard move to swallow, though in all honesty, Unity was better (though pretty buggy and laggy until the end)!

When Ubuntu have removed Gnome2, I have looked at Unity, got really unhappy about it and installed gnome3. ... In a few minutes, I started to think that Unity wasn't THAT bad, after all, and went back to it.

Now when it is gone, I'm using xfce, which seems be the last decent desktop environment.

Another one to add:

Besides waiting for animation, in Windows 10, if you type the password fast enough the first character gets selected and the second character you type will replace it.

This happens frequently.