It's a prompt to install our app...it's legit and if you want you can give it a try. If you don't like it, you can uninstall it (click the 3 dots in the toolbar and select Uninstall). This is how it looks:
A few months ago we've released the MalwareTips app - Feedback - MalwareTips Mobile App Is Now Available. This app is bulit on the Progressive Web App framework, and the browsers that are supporting PWA will show these notifications. We've built the app for mobile users, however, you can now install the app on Mac or Windows without any issues.
Starting with Chrome 77, users will see a + sign in the URL bar when they browse sites that support PWA.
The app is basically using Chrome as a base, so you should have all the features of the browser + your extensions in the app. Like I've said, we've built this for mobile users, however, you can give it a try and see if you like it on Windows. It's easy to install and uninstall so there's no reason to try it out.