I had this issue when I was trying to land flutter/plugins#4608. I got this error:

No version change found, but the change to this package could not be verified to be exempt from version changes according to repository policy. If this is a false positive, please add a line starting with
No version change:
to your PR description with an explanation of why it is exempt.

So I updated the PR description and re-run the check, but still not working.

I suspected that it's because the PR description is not uploaded after edited for some reason. In order to verify this assumption, I rehashed the commit, which will most likely trigger the whole pipeline, and the error is gone.

For now, I figured that it may be helpful to include this as temp workaround in the error output.