New extensions that come with the canary version.

[Tenero]

I have used the Canary, but found a problem - there is a new extension in the extension folder, but I can't see this extension in the extension management of the browser, I don't know this extension what is the role of.The ID of this extension is "jmjflgjpcpepeafmmgdpfkogkghcpiha"

[#2]

It seems not an ordinary extension.

If you looked into manifest.json under that folder, you could see its name and description.
>"name": "Update CWS CTA Button",
>"description": "Change CTA on CWS from 'Add to Chrome' to 'Get' and 'Remove from Chrome' to 'Remove'",
Try visit Chrome Web Store thru the link on edge://extensions page and move to any extension's page. 'Add to Chrome' button is displayed as 'Get'.
Since this feature(msEnableCWSButtonUpdate) is in Experiments/Field Trials, it works when msEnableCWSButtonUpdate is enabled. Whether it is enabled or disabled depends on configuration service(online).

[#3]

Thanks, but what is a CWS CTA?

[#4]

CWS => Chrome Web Store
CTA => Call to Action

So, as noted by atlanto, this is the thing that changes Chrome's Extension Web Store to tell you you can install the extension into Edge.