"4. User Generated Content
Any content that you create, generate, or make available through the Epic Games store application shall be “UGC”. You hereby grant to Epic a non-exclusive, fully-paid, royalty-free, irrevocable, perpetual, transferable, and sublicensable license to use, copy, modify, adapt, distribute, prepare derivative works based on, publicly perform, publicly display, make, have made, use, sell, offer to sell, import, and otherwise exploit your UGC for any purposes, for all current and future methods and forms of exploitation in any country. You may not create, generate, or make available any UGC to which you do not have the right to grant Epic such license. In addition, you may not create, generate, or make available any UGC that is illegal or violates or infringes another’s rights, including intellectual property rights or privacy, publicity or moral rights. Epic reserves the right to take down any UGC in its discretion."
Literally says "hey give us the ability to exploit your works". Before you state Steam says the same, let me quote someone here on the difference.
"So basically, Steam's EULA is restricted to content uploaded to Steam, and Valve is only allowed to use the content for the purpose of Steam promotion.
Epic's EULA is not restricted at all, may apply even to recordings of games played on the Epic store uploaded on Youtube, and may be used for literally any goddamn thing Epic wants to. You could upload a mod for the original Unreal to the Epic Store, and by doing so you'd grant Epic the rights to sell the mod and make money off of your creation. By making a Let's Play of a game hosted on the Epic Store, you'd grant Epic the right to monetize your video. Valve is simply not allowed to do that with their license."