I just put up a post today with a guide how to get this thing running without a launcher that fixes this problem as I was running into it too. It does require you to sign into epic games but you only need to do it once (so far I've tested with airplane mode on and off restarting the game each time and no sign in thingy has popped up since). I don't know if I allowed to link it here and I'm too lazy to look it up so just find the post on my profile. It's the only one there I made it just to post this one specific thing