Probably stay off TLOU related forum threads then. I'd avoid making threads like this too.
You're surely not new to this, it's the same with any new release. Avoid related media if you want to avoid spoilers or leaks.
It's unlikely that you'll see a leak for the narrative in a headline, at least not on ERA, so stay away from threads and forums that relate to TLOU just to be safe, and I think you'll be fine.
Who does OP think is going to leak it? Naughty Dog employees?
In general I think the weakest point security wise is the playtesters that these studios get in. Most of Sony's games are played by 100s if not 1000s of players prior to release, all of which are NDAed, but it can be challenging for studios to hold them accountable.
A lot of those leaks actually don't get seen by anyone though. I remember working in industry and we'd see leaks here and there, some random would post the narrative on Facebook, 4chan, twitter or some place, and would either ignore the post or not believe it was real.
I remember seeing one wherein someone leaked the narrative for a popular video game series, and the guy got bashed for making stuff up, with folks saying his story was too unrealistic.
Kind of like how the Apex Legends map was leaked one year prior to the games release and everyone just dismissed it. That's a good example.