According to https://csp-evaluator.withgoogle.com/ the CSP built here is NOT valid (and the blob: value is missing at img-src, so the image is not displayed when reading ebook in a browser)
Before this commit, in Chrome response header you can find
Content-Security-Policy: default-src 'self' 'unsafe-inline' 'unsafe-eval'; font-src 'self' data:; img-src 'self' data:; object-src: 'none'; blob:;style-src-elem 'self' blob: 'unsafe-inline';
After :
Content-Security-Policy: default-src 'self' 'unsafe-inline' 'unsafe-eval'; font-src 'self' data:; img-src 'self' blob: data:; object-src 'none' blob:; style-src-elem 'self' blob: 'unsafe-inline';
and image in viewer are displayed