There's a bug in Bloodborne that makes the game noticeably easier if left running for too long.
Potentially a memory leak, the glitch was spotted by Redditer meatballz, who posited that if you leave the game running for more than 12 hours or so the bosses will cease to function properly and use only a fraction of their movesets.
"There's a memory leak issue in this game that causes bosses to have a reduced moveset after the game has been running for a long time," meatballz said in their original post. "I wondered for a long time why so many bosses in my initial playthrough seemed so easy. Turns out I'm not just a Bloodborne badass who can one-shot the bosses other people have trouble with, it was because I marathoned the whole game in one sitting and around the 12-hour mark bosses became much simpler."
Some commenters are saying this bug will occur even if the PS4 is in Rest Mode. meatballz also noted that the 12-hour mark is just a rough estimate.
Here's a video comparison showing the difference in behaviour between a late-game Bloodborne boss running as it should, and the "easy mode" version where the game has been running upwards of 12 hours:
Redditer Selekah added a few additional notes regarding how this bug affected bosses in their game (mild spoilers follow in terms of boss names):
- Mergo's Wet Nurse did nothing but walk towards me while flailing. No dark cloud phase. She was basically stuck walking towards me like a slow lawnmower.
- Micolash did nothing but try to hit me with his fists. No tentacle attack, no cosmos attack.
- Ebrietas repeatedly faceplanted and spit blood at me. No cosmos attack, no forward lunge, no variations.
- Logarius just used his scythe attack, zero spellcasting. He was permanently stuck swinging at me like this.
- Abhorrent beast did nothing but his 3 hit combo in every phase.
We're not sure if this is a "memory leak" per se, but it is some sort of widely reported problem. We've requested comment from Sony on the matter and have yet to hear back. Hopefully this will get patched, but in the meantime to get the most out of Bloodborne you'll want to turn your PS4 off every now and again.