Downloaded file differs from original

As a test, I tried to transfer https://github.com/freedomofpress/dangerzone/releases/download/v0.3.1/Dangerzone-0.3.1.msi to myself using https://file.pizza/ in Firefox 115.21.0esr on Windows, with the receiver tab in a Private Browsing window, and found that the received file had some differences to the original in several places (comparing with Beyond Compare or `fc /b`). The file sizes were the same, though. Tried a second time and the received file differed again (from the original and from the first received file). Tried it with a smaller .pdf file and that was received correctly.