Google is beefing up the protections in Chrome's Enhanced Safe Browsing mode, which the company rolled out in 2020 to add an extra layer of security. It'll add new features centered around extensions and downloads.
If you have Enhanced Safe Browsing switched on and you're about to install an extension from the Chrome Web Store that isn't part of a trusted list, you'll see a popup informing you of that. Currently, around 75 percent of extensions are considered trusted. To have their extensions designated as such, developers need to abide by the Chrome Web Store Developer Program Policies. New developers need to stick to the rules for at least a few months before they're considered trusted.
If you see the dialog, that doesn't necessarily mean the extension you're about to install isn't safe, but it's worth exercising caution, just in case.
In addition, Enhanced Safe Browsing will have increased protection against malicious downloads. Whenever you download a file, Chrome first uses Google Safe Browsing analysis to determine if it's possibly suspicious. If Safe Browsing thinks a file is risky but not obviously unsafe, you'll see a warning if you have Enhanced Safe Browsing activated. It will ask if you'd like to scan the file for a more detailed analysis.
Chrome can then upload the file and once it's scanned, you'll see another warning if Safe Browsing believes it's unsafe. You'll still be able to bypass the warning and open the file, but it'll be at your own risk. Any files uploaded to Safe Browsing are deleted soon after they're scanned.
Google says it will roll out these features starting with Chrome 91, the current stable build of the browser. As such, they should arrive in Enhanced Safe Browsing soon.