That’s called a zero day.

I’ve heard that’s installed through Google Play Services so you get it even if your phone is no longer receiving timely security updates from the manufacturer. How considerate of them…

Not necessarily. If his paranoia makes him think that you’re out to get him, do you trust him to have more control of your phone than you do?

The way you normally do this for Word documents is Track Changes. Microsoft Word and Libre Office also have a built-in way to compare two documents, in case you didn’t have Track Changes enabled. I assume if they’re asking for document history, they want to see what changed when revising your draft, not in what order you pressed the keys. Although personally I tend to revise back the past part of the document as I’m writing instead of writing multiple drafts and this wouldn’t really work for me. I guess another option is just to use set a timer and save a new version every so often. Maybe there’s a trick you can do with scripting to make copies of your autosave file and then combine those into a format your teacher can understand.

Using Git is out of touch. It’s incredibly unlikely that a language teacher understands Git or cares to learn how to use Git.

It sounds like your teacher probably has a way they expect students to do this, probably Google Docs or Office 365. Both of these have web versions so you could use them even if you’re running Linux.

Are there plenty of replacements? The only RCS implementation on Android that I know of is Google’s. The gallery and keyboard are practically unchanged in about a decade. Finding good keyboards is difficult, especially if you need languages besides English. I ended up installing a keyboard with too many permissions from Google Play and just blocking the extra permissions.

How long until an American AI company takes credit for it?

This looks more comprehensive than Untracker, but maybe it is too complicated for some people?