Afaik, in order for workbox precache to keep track of precached files, a md5 hash is created of the file and used as the file's revision number in sw.js (see get-asset-hash.js and generate-sw.js)
After fetching the file, does workbox create a md5 hash of the new file and compare its value with the revision number in sw.js?
Workbox doesn't seem to check the integrity of the new file via md5 (see PrecacheController.mjs, cacheWrapper.mjs and PrecachedDetailsModel.mjs)