From the release notes:
When you drag and drop files from your native file explorer into Obsidian, it will now default to creating file:/// absolute links. Holding the Ctrl/Cmd key will copy the files into your vault like it did previously.
This is not the case for me, on Mac, holding CTRL while clicking on a file in Finder opens the right-click actions menu, and when holding COMMAND and dropping a file into Obsidian it just bounces off and doesn’t insert it.
It seems the only way to add image attachments now is to either use absolute paths in standard Markdown image links, or manually move the image into the attachments folder and drag a link from the left sidebar to create a non-standard Obsidian markup image link like ![[Screen Shot 2021-02-17 at 9.22.04 am.png]]
Neither really seems ideal, but I was perfectly happy with the previous behaviour of being able to simply drag and drop images from finder and let Obsidian copy the file into the attachments folder and insert its own image tag.