It's a glitch that's probably used in speed runs or BL4 runs in Bloodborne, but it's also one I've encounter naturally. Sometimes, when fighting Orphan of Kos and parrying at the correct time, maybe a few times in a row - can't remember - you can make Orphan just stop attacking altogether. He basically just chills and does nothing.

And there was probably some other glitch - I vaguely think there was one - when I was playing Khazan? I remember struggling with one particular boss and it somehow glitching out, basically also stopping all attacks and becoming a punching bag. Can't for the life of me remember who it was, though

Not in Elden Ring, but a few times in other games.

In DS3 I was summoned to help with Dancer, and she somehow managed to grab me and the host at the same time. So we were about 15 feet apart, me in Dancer's hand, and host floating in mid air both going through the grab animation.

There was another time in DS3 in the Cathedral of the deep. The first giant hit me and knocked me into a small corner between the short staircase on the ground floor and I was stuck there, had to bone out.

And another glitch in Cathedral where I clipped through the ceiling while riding the elevator and went out of bounds - here's a YouTube short of it that I captured and also mention the above glitch https://youtube.com/shorts/g1mHaiism_k

In DS1 I had Moonlight Butterfly glitch out. It spawned much further away from the bridge than normal, and it was rotated 90 degrees so it was facing perpendicular to what it normally would be (facing towards the arena entrance rather than facing the bridge). I forget what happened, but I think I had to save and quit out to make it reload properly.

Huh, I thought they had "fixed" that bug. Originally the problem was that if you were playing co-op and/or had ashes summoned and then ended her first phase with a riposte, her second phase would spawn with 1 hp and not do the normal opening moves. There was a patch that was supposed to make ending her first phase with a riposte just... not do anything, because apparently that was the closest to an actual fix they could figure out. I have no idea why that patch change didn't take effect for you (assuming that the riposte thing is what happened, it's the only version of this glitch I know about)