The standard minimum withdrawal is 2 mBTC, as it has been this way for many years.
Some promos will have different terms, so if the term is that the MAX withdrawal is less than 2 mBTC, the withdrawal minimum is dynamically reduced to match this (say it is 50 free spins, with a max withdrawal of 1 mBTC, then the minimum withdrawal for you will be 1 mBTC - of course it must be, as MAX cannot be less than MIN). This is all done magically by the system 🤯

Also, once you are a regular user after a while, the minimum can be reduced to less than 2 mBTC - this again is done automatically by the system based on each user deposit and bet activity.

So the minimum is NEVER more than 2 mBTC, but it can be less - always you are told what this is when you claim a promo, or in the withdrawal screen at any time.