That’s showing limit-2, rather than just limit. The length of the final encoded data has a limit of 4,194,303 bytes.
Lua value --> (JSON encode) --> JSON data --> DataStore
^
|
Limit enforced
4,194,301, on the other hand, is the effective limit of a simple Lua string before it is encoded. The difference is caused by the overhead produced by the JSON encoding. Other Lua values will produce different amounts of overhead, but the final result of the encoding will always have a limit of 4,194,303 bytes. Sorry that I wasn’t clear on this.