This all comes down to the ongoing Epic vs. Apple lawsuit that started in 2020.
As you probably know, the conflict of interest began back in 2018 when Fortnite became available on mobile devices. Before that, Epic Games' co-founder and CEO Tim Sweeney had said that the 30% revenue sharing cut the digital storefronts earned off every purchase was not really fair especially in mobile gaming. Tim's reasoning was that the 30% made sense with PCs and consoles where expensive hardware adds to the cost of the product but mobile game storefronts could easily reduce this number to 12 or even 8%.
Consequently, when Fortnite mobile came out Epic tried to bypass Google Play Store and Apple's regulations to move forward with its own pricing policy. On Google Play Store, Fortnite was listed as a sideloaded package (so that Google would not take part in any of the microtransactions in the game) but this resulted in an insane amount of fake games so the package was taken down and Fortnite was released as an official game.
In August 2020, Epic announced that players who purchased in-game items for Fortnite mobile through their official website would receive a 20% discount. Both Google and Apple took the game down within hours as this was against Google Play Store and App Store's policies. In September 2020, Apple filed a lawsuit against Epic as the developer went against the terms and conditions of the agreement the two parties had signed.
That, however, is not the only reason why the Epic Games Store is struggling with profits. The platform is generously offering free games to its users and the list of Epic's free-to-play games includes numerous major titles (if not monster titles) that have millions of dollars invested in their development. Fortnite, Genshin Impact, Dauntless, and many other well-known titles are free to play with profit coming only from the in-game purchases. Plus, on Epic Games Store you can find numerous games that you can try out for free for a limited amount of time. Some players think this might be a wise decision in the long run and thus far Epic "have the money to do this". They suppose that with this many popular titles being released by Epic and with their bountiful free-to-play approach, the company might one day take over the rest of the digital storefronts and have the majority of players get their games through the Epic Games Store.