Since launching Data Stores years ago, the service limited storage to a maximum of 256KB data per key. Since then, games and experiences have only grown to be bigger and more immersive, and developers have had to implement some workarounds in order to save an ever-growing amount of player data.
To address this, as of today, we are increasing the DataStores per-key data limit from 256KB to 4MB!
Note: Request limits for reads and writes are going to stay the same, as is the per-key throughput limit. (https://developer.roblox.com/articles/Datastore-Errors)