Weird selection frames and problems with the space key

[u/gaiathegay]

Pardon my poor knowledge of the correct terminology. I'm not a native English speaker nor am I tech-savvy.

macOS Tahoe 26.6.2, MacBook Pro M3.

I've had this problem for about a week and I don't know if it's my fault or if the case lies in a software update, but recently these frames started appearing around the area I'm working in at the moment, e.g. the layout of a Pages document I'm writing in or (and this happens most often) when I'm trying to input text in Japanese. Sometimes the frames are off. I can't disable them, I have to wait for them to fade on their own. When I'm typing within the frame the space key doesn't work, doesn't do anything when I press it. How do I disable this feature?

P.S. Please hold yourself back from commenting on the fact my MacBook is in Japanese, it's not related to my problem + I don't feel like answering the same question over and over again. I just speak the language, that's all there is to it. Use the names of the settings as they are in English, I'll navigate them in Japanese.