https://www.pcgamer.com/epic-steam-data-reddit/

Epic Games has responded to accusations that its launcher is secretly mining users' Steam data, saying that the information it collects is used for multiple non-nefarious purposes including its Support-a-Creator program, communicating with the Unreal Editor, and importing your Steam friends list should you opt to. The launcher does scan for active processes, but Epic's vice president of engineering Daniel Vogel said that it does so to ensure that games don't attempt to update while they're running, and that the data is not sent to Epic. 

Worries about the Epic launcher's data tracking were sparked by this lengthy Reddit post, which claims, among many other things, that the app enumerates running processes and attempts to access DLLs and root certificates without notifying the user. The author also claimed that data was being transmitted to Epic for unknown reasons, and that it stores hardware information in the registry.