Signal may not be preserved across format changes

## Description
The signal may not survive multi-generation copying of a work that is permissible under the license

## Reproduction
1. Author publishes a web page and applies a CC license and a CC signal.
2. A user of the web page makes a derivative work that is allowed by the license, in a medium that does not support the CC signal. (For example, a printed copy)
3. A user of the derivative work from step 2 makes a copy without the CC signal in a medium that does support the CC signal (For example, scans or OCRs of the printed copy)
4. The work is included in a generative AI training set even though the author took steps to exclude it.

## Expectation
The license could be updated to require the signal to be preserved and re-applied when the work is made available in a medium that supports the signal.

## Resolution

- [ ] I would be interested in resolving this bug.