Elden Ring has many challenging moments and notoriously difficult fights, but no traditional boss is as consistently tough as grappling with random world geometry. Pre-nerf Starscourge Radahn was a force to be reckoned with, and Malenia, Blade of Miquella is still impaling players left and right, but rocks, trees, and unexpected ledges are probably responsible for more deaths than those two combined. The Tree Sentinel isn't all that tough once a few levels have been gained, but they've conspired with the surrounding landscape to hinder maneuverability.
FromSoftware's jump to an open world with Elden Ring has been widely celebrated, but it has introduced a comically frustrating occurrence where the terrain frequently contributes to the player getting killed. For every exciting discovery in Elden Ring, there's an equally wacky place to accidentally get stuck while fighting a difficult enemy. This isn't really a serious issue with the game, just an unfortunate side effect of gameplay mechanics. Other open world games suffer from similar quirks, but it can be especially anger-inducing in a demanding game like Elden Ring.
Gravity has always been a common cause of death in FromSoftware's Soulslike games, from Dark Souls' seemingly inconsistent fall damage to Sekiro: Shadows Die Twice's platforming sections near bottomless pits. Every once in a while world geometry would play a part in that - a slope inadvertently pushing the player to their doom, for instance - but the tightly designed levels usually avoided the issue that seems more common in Elden Ring.
Elden Ring's Random World Geometry Deaths Are Unavoidable
Most bosses required to finish Elden Ring's story don't have this issue, because it crops up most commonly when fighting optional ones somewhere in the open world. When there isn't an arena tailored to the encounter, there's not much FromSoftware can do to ensure a player doesn't get stuck on a tree or back off a ledge. Players get so focused on the boss, and with the camera fixed in one direction while locked on, it's sometimes impossible to keep track of all the surrounding shrubbery. It's not just boss encounters either, and dodging attacks from a Giant Crab or Flame Chariot can easily lead to the same thing.
Getting stuck on a rock does seem to happen more frequently against Erdtree Avatars, Night's Cavalry, and the like, though. Bosses often have long attack combos, and it's easy to bump into something while waiting for an opening. At least it's not like getting stuck in mid-air in Elden Ring, where a quirk of the fall damage system seemingly kills the player. Luckily, for all the times Elden Ring's terrain has directly contributed to the player's death, there's likely an equal number of circumstances it's been used to stealth attack enemies or deliver an incredibly cool jump attack from above.