More detail instructions for OP's post for those who are confused. This is done from the browser on my laptop, I don't know what they look like on phones.
When you click the first link gemini.google.com/extensions, you need to click on the setting icon at the bottom, then choose "Extension", like this:
Scroll down a bit, you will see the options, turn them all off.
Then, you click on the second link myactivity.google.com/product/gemini, you'll see it tells you that it's already "turn off". NO! IT'S NOT! You have to click on that "Turn off" option, it'll drop down a menu like this:
Turn that thing off. Until that button shows you have to click to turn it back on like this:
And then, click on the delete button down there too, even if it says there's nothing to delete, just do it as a caution.
After you's done with those two. You go to your Drive, find the Setting button.
Click on the "Privacy" tab, choose the button "Manage Workspace smart feature setting"
Tick both of those off, then click Save. Or if you still want to use Google AI assistant for some reasons, please read the fine lines very very carefully.
Only then, you can feel safe enough with this force AI assistant bullshit. FOR NOW 🤡 All these steps still can't get rid of that Gemini blinkblink icon though >:(((((
Repeat for every one of your google accounts 💀