Forge 1.12.2 literally corrupting itself on download after trying to launch Minecraft

Failed to download file.
Name: 1.12.2-forge-14.23.5.2855.jar
URL: https://s3.amazonaws.com/Minecraft.Download/versions/1.12.2-forge-14.23.5.2855/1.12.2-forge-14.23.5.2855.jar
Filename on disk: 1.12.2-forge-14.23.5.2855.jar
Path: C:\Users\insert-username-here\AppData\Roaming\.minecraft\versions\1.12.2-forge-14.23.5.2855\1.12.2-forge-14.23.5.2855.jar
Exists: File

I get this every time I try to start Minecraft Forge, but is there a fix for it?

As an additional measure to make sure I don't misdiagnose it as "corrupted", I opened the .jar file in \.minecraft\versions\1.12.2-forge-14.23.5.2855\ as a ZIP archive and indeed it couldn't be opened.

However, something quite funny happened in the logs window: A ton of text written in the language of my PC appeared, with the letter "é" appearing as a question mark inside of a diagonal square.