A very active Reddit post discusses graphic card temperature spikes caused by the Epic Games Launcher, even when the program is idle. The hot hardware experts at Hot Hardware discuss the details of what's going on:

Ultimately, these CPU temperature and usage spikes are not typical of game launchers. When experimenting with the Steam and GOG launchers, CPU idle temps and usage remained nominal and much lower, after an initial brief spike on loading. So what exactly is happening with the Epic Games Launcher that idle temps are spiking and CPU usage is unnecessarily engaged?

Doing some testing on another personal machine, we noticed that the Epic Games Launcher has five different processes open at one time. Out of curiosity, we opened up Glasswire, which is a free network traffic monitor. We could see that the Epic Games Launcher and associated processes were firing off data at regular intervals to over 22 different servers. This was happening whether we had the launcher open, minimized, or in the background. The larger spikes shown in the Glasswire graph below are from when we reopened the Epic Games launcher after closing it.

Another interesting discovery is that the “EpicWebHelper” sent some data to the following URL:

    tracking-website-prod07-epic-961842049.us-east-1.elb.amazonaws.com

Over the course of approximately an hour, Epic Games sent more data than 514KB of data to some server(s) somewhere. This is more than 14x what Steam and NVIDIA GeForce Experience sent in the background during the same timeframe. While it remains to be seen if the data collection is the cause of the CPU usage issue, something smells fishy here. In fact, it may be advisable to kill off the Epic Games launcher for now, when you're not actively using it.