How to get rid of "finalize the string" box when typing in another language? [closed]

I'm using Windows 10 to type in English and Japanese and I'm using the Japanese Windows 10 IME.

When I type in Japanese but not inside a textbox (e.g. in File Explorer if I just press a key without being in the middle of renaming a folder or anything).

I get this annoying box:

When I'm in Japanese input mode:

And it interferes with keypresses (hotkeys/shortcuts/etc.)

How can I get rid of this box? Nothing I've read elsewhere (older Stack Exchange posts, Reddit and even YouTube) works.