What are the monthly withdrawal limits?
There is not even a single word about that in TOS -
https://luckydice.com/en/legal/terms-of-use .
There is only:
In case of large withdrawals manual processing may be implemented. Manual withdrawals are processed on business days from 10:00 to 18:00 GMT.
In case you want to use luckydice as exchange (that's why you ask for monthly withdrawal limit)
Exchange must not be used for personal use, not related to the game. It is prohibited to deposit money for the sole purpose of exchange and withdrawal and not making bets.
So I guess there is no monthly withdrawal limit.