With the previous update removing the legacy image attachments, the latest update – 5.0.2 – allows custom image IDs such as:
[ecard id="1, 2, 3, 4, 78"]
The IDs correspond to images in your Media Library. This feature eliminates the need to manually attach images and also eliminates the need to upload the same image multiple times, just to have it attached to different posts or pages.
This update also helps with the missing Add Media button in the block editor, which was heavily used to attach images to posts.