In the release, fabric.mod.json is invalid because of an unexpected end of string. (Unexpected end of string, json(258))

Source code (in this repository):
"description": "Makes the loading screen darker\n\nIn-game configuration is only available in 1.16.2 and later."

File in the compiled JAR:

"description": "Makes the loading screen darker

In-game configuration is only available in 1.16.2 and later."