We have code for two different cache formats for Chrome (and derivatives) use and third different one for Firefox. So it's no surprise that Firefox can behave differently.
I don't see any issues with
https://www.fanfiction.net/s/8096183/69/ on Chrome on Win10, nor Chrome on MacOS.
I don't think I can help with this any further without seeing a copy of cache files that are failing. If you're clearing your cache anyway, it should be small enough to zip up and not contain anything private.