It's been there for several versions now. Its disabled by default and only shown if you have your normal menu bar hidden, because large programmes like kate with a lot of options needs the classic menu bar for ease of access.
So nothing for you to worry here.
( And even if it were the default, checking the show menu bar button would probably be easier than switching to something new, don't you think? )
@Bro666 I wasn't aware of CTRL+M
This makes my day thanks!
(Then I'll maybe reconsider other applications for which hamburger seems to be the default...)
I always use classic menu and never saw that the hamburger menu already exists in Kate 😅
I was so afraid when I saw the screenshot :ablobcatknitsweats: