Some people have been finding games have been disappearing from the epic launcher that they bought. Mostly free ones but the current "resolution" is for people to pay for them again which isn't great. It seems like there is some sort of link with games vanishing from an account on an uninstall or some such with them not being listed in the account purchase history.
I went through my list of games and found 8 of them not listed in the purchase history two of which were ones I'd paid for including Satisfactory (although there was a code redeem for that but I'm pretty sure that was the free open beta weekend)
It might be worth going through and checking all the games you have are listed in purchase history, with games that you paid money for you should get an email confirming the purchase but for any of the free ones it seems epic doesn't do this.
Anyway they seem to be investigating so perhaps they will fix it but if you find any gaps in the history it might be worth raising a support ticket about it just in case