FromSoftware nerfed some of Elden Ring's trickiest boss fights without telling anyone. Several twin bosses, like the twin Crystalians or Mad Pumpkin Heads, have had their aggression dialed back to make those fights much easier to manage as a solo player. The change was made in patch 1.04 but wasn't clear in the patch notes. Dataminer king bore found the changes in April and Illusory Wall demonstrated it in their latest video.
Before the changes, fighting two bosses at the same time required you to dance between their overlapping attacks. Now, boss AI is less aggressive when they're not the one of the twins actively attacking you, and the game now generally de-emphasizes bosses attacking at the same time. Fights that were once chaotic as two enemies tried to pummel you are now a lot easier to get a grip on.
Elden Ring gitguders might say this makes the game more casual or whatever, but the changes to boss AI help prepare you for the fights that weren't changed like the twin Gargoyles or the Godskin twin. Anyone that's played a Souls game knows that so much of the game is designed to teach you how to approach harder fights later on. It makes Elden Ring more consistent and also more approachable for people who haven't played every previous FromSoftware game.
Illusory Wall shows off a bunch of other changes—both big and small—to the game that weren't explicitly noted in the patch notes. The Merciless Chariot enemy that rolls up and down the hallways of certain dungeons and one-shots you now might not instantly kill you, for example. Other changes include enemy hitbox sizes and the removal of one leftover chest from Dark Souls. For some reason, they left the others in.