I think minimum withdrawal should not be fixed as long as Credit-Satoshi conversion is not fixed. It should be automatically adjusted according to Credit-Satoshi conversion.
The higher Bitcoin price rises, the harder it is to get Satoshis. Now, BTC price is above $4000 and the Credit-Satoshi conversion rate is 0.2053 only. It can take a year to reach the minimum threshold (50k Sat) if BTC keeps rising like this. Look at your account, your Satoshi will not increase or even become lesser and lesser if BTC price goes rising.