Hah, what fortunate timing!
I just finished The Last Guardian the other day on my PS5.
Originally I started with the Rev 1.0 version since I have the physical disk and disabled my internet connection so the game wouldn't update.
The problem with the 60FPS mode is two fold:
First there are scenes in the game which will freeze on the PS5 with the 1.0 version. The first is when you have to push a glass eye off some scaffolding and have Trico grab you before falling to your death.
Second, the game looks completely flat in 60FPS mode.
My personal experience:
Started off at 60FPS mode and I liked the high framerate but could tell everything looked very flat.
I continued this way until I hit the first bug which forced me to install the update.
With the update installed the visuals got sooo.much.better. Everything had depth, warmth, and life to it unlike the 60FPS version.
Additionally it seemed like a very smooth and consistent 30FPS, so while not ideal, it's a very fair compromise.
So instead of patching the game to get past a freeze, then uninstall the game entirely, then disable internet and install again every single time there's a bug I stuck with the 30FPS mode and I have no regrets.
The game looks AMAZING and, in my opinion, the 60FPS mode is completely lifeless. Like, the better visuals, in my opinion, in 30FPS mode enhance the game and totally make it better.
Compare that to my recent TLOU:R play through on the PS5 where 30FPS mode is miserable and 60FPS all the way.