Steps to reproduce: 

• Create a new world and navigate to saves\<new_world_name>\datapacks
• Create a new datapack in this folder, just use a default .mcmeta file
• Rename the folder adding the '§' obsolete color formatting character somewhere in the name: §a§lExample Datapack Name in Green Bold§r
• Load the world, check the § character is working by running /datapack list
• Type in /datapack disable and tab autocomplete the command.
• Running this command kicks the player for "Illegal Character in Chat" as expected, due to the '§' character, but doesn't disable the datapack.