P: The filter continue to filter on the second character I type. And third charcter etc.

I’m guessing that’s on the desktop? If so, have you tried typing it into the search box at the top, rather than in the Keyword pop-up? I’ve found that much more keyboard friendly, including being able to type additional characters in the word.

What version of Lightroom? If I try this in Lightroom for iPad (typing this on my iPad) then the search works as expected. If I type three characters, then Lightroom displays a list of only those keywords that contain these three characters (but not necessarily as the first three characters).