I didn't pay much attention to updates, but about a week ago kate started scrolling in full lines.
For example I've got line with 500 characters and it's warped to 5 pseudo-lines by 100chrs. In the past I would've scrolled by pseudo-lines, and now each scroll takes a full line.
When line warped more than 10 times kate becomes completely unworkable.

I want to make it like it was before.
kate 5.0.0

Good luck. I filed this bug in 2010: https://bugs.kde.org/show_bug.cgi?id=256561. It was fixed at some point and then the bug was reintroduced recently. It's been reopened, but it doesn't look like anyone has the time or motivation to do anything about it. They tried to fix it during a kate sprint but didn't succeed. That was in October last year!

If you want a decent qt5 text editor, try notepadqq. Otherwise, I've reverted to opening all my text documents in the latest stable Kile which uses KDE Development Platform 4, and scrolls normally.

Try this:
Settings->Configure Kate->Appearance->Uncheck "Dynamic Word Wrap".