BMV

Stark is correct. That points to the chat count which is relatively easy to find in cheat engine and is found 0xC after the chat base. I just copied and pasted the address I find directly without "fixing" it.

I sometimes use a relative offset to another offset when things are located closer together because their relative distance is unlikely to change in future updates. It's just to make things more maintainable.

I do not use chat functions at all but I guess this 0xFC6930 might be just an address that is easy to find ... for example by searching for the number of messages in the chat.

and the base is just reduced by 0xC .. so:*
$ ADDRESS_CHAT_BASE = 0xFC6930 - 0xC means
$ ADDRESS_CHAT_BASE = 0xFC6924‬