This issue happens when there is an image that is tagged with multiple tags.
For example, image with digest of sha:123 has tags of master_123 and releast_123, and the regex to ignore is release_. So anything that matches release_ should not be deleted. However, since the image with sha:123 is also tagged with master_123, it is deleted as well.
The expected behavior would be that this image is also ignored and not get deleted.