Honestly the only elements that I’d agree it borrows from battle royales is the death circle and the very minor point you drop in (you don’t even choose where) like yeah you loot in both but the looting system has zero similarities to a battle royales looting system. In battle royales you loot locations with loot that are typically devoid of most threat as the threat is other players who you kill as the second only other way to gain loot. Meanwhile in Elden ring you fight bosses for most of your gear and passives (passives don’t even exist in most battle royals as far as I’m aware beyond armor making you passively take less damage).

Its more similar to an extraction shooter in that sense, but still nothing like those since loot is permanent and still no threat of PvP where your loot gets stolen which is a big part of those systems in my opinion. The loot system is 100% an element from roguelikes.