How do I get rid of this annoying search suggestion that's really unhelpful?

When I try to type in a native search bar of a website, I often times get this search suggestion.

Not only this is not helpful at all (because why would I need suggestions of one website’s search for another website?), it’s sometimes downright annoying.
How do I get rid of it?
There was already a forum post about it, but there wasn’t any solution. Some people suggested it’s a problem of the keyboard, not the brave suggestion setting.
Of course, if you go to Brave > Settings > Appearance and turn off all the check boxes for search suggestions, you get rid of suggestions for the brave search bar. But not for the suggestions of native search box of many website as I mentioned in my image.
Can anyone help me with this?

There is a technical reason why they randomly appear when you click on a input box.
But basically when you make use of those old input box, they will be written in a file, and every file matching the ‘name’ of that box will display the same autofill information.

You can remove it by shift+del one by one, or remove the autofill from the Clear Data → Advanced (ctrl+shift+del)