This is an update to my post from last week Important Information Regarding the Safari Extensions Gallery, which described an email I received from Apple Developer Relations warning that the Safari Extensions Gallery will no longer be available in September 2019. I was expecting this to happen at the end of September, presumably when macOS 10.15 Catalina is released to the public. However, yesterday afternoon I received another email from Apple Developer Relations, just 8 days after the first email. The new email said that the Safari Extensions Gallery is no longer available. And indeed, the previous URL of the Safari Extensions Gallery https://safari-extensions.apple.com/ now redirects to the Mac App Store in Safari, while the URL completely fails to load in other web browsers such as Chrome and Firefox. The Safari Extensions Gallery is officially discontinued.
My own extension StopTheMadness is in the Mac App Store, so it's unaffected by closing of the Safari Extensions Gallery. StopTheMadness is already compatible with Safari 13 and Catalina.
Here's the text of the email from Apple:
As a final reminder, the Safari Extensions Gallery is no longer available. Users on macOS High Sierra or later can easily find extensions on the Mac App Store by choosing Safari Extensions from the Safari menu.
To make sure users can take advantage of your extensions on the latest versions of Safari on macOS, we recommend that you convert your Legacy Safari Extensions (.safariextz files) to the Safari App Extensions format and either submit them to the Mac App Store or notarize them for distribution outside the Mac App Store.
And here's a screenshot: