I think I know when it appeared to be happening. I had recieved some SMS text message from my bank regarding transaction item. And there was some special weird symbol, which looks like vise versa question mark.
I had something with macOS Notes, when I opened it and it just crashed. So I just cleaned all content in Notes in iCloud web. And was able to use macOS Notes again.
Is there any way I can clean all text messages in Messages app on iPhone?
I have removed everything, it seems in Settings -> iPhone Storage -> Messages:
But it keeps closing in right after I open it to write someone a reply. So basically I just can view notification previews and can't send a reply to anyone.
I have in mind some ways of fixing it. Like restore/refresh or wait for next iOS version to fix it or refresh it somehow.
Though, I don't want to restore the phone, settings or whatever. Might just probably wait when it cleans messages older than 30days of new iOS version will come up.
Best Answer
iOS 11.2 did it. But what was the issue itself, who knows.