Looking into "minimum withdrawal amount" comes down to adding up costs. The price of moving money in and out of a casino is rarely one number. A fee can come from the operator, the payment method or the bank, and a currency conversion can hide inside an exchange rate that looks close to the market one. Laying the parts out before the first deposit gives the real cost of every payment.
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Minimum amounts turn small balances into a cost of their own. A withdrawal minimum above the money left in the account keeps that money in play, and a deposit minimum set higher for some methods pushes players toward a larger first payment. Some casinos also charge an inactivity fee on accounts left untouched for months, which slowly drains a forgotten balance. Both limits are printed on the banking page, usually in a table by method.
Currency conversion is the cost most often missed. When the account, the deposit method and the bank use different currencies, money can be converted twice on the way in and twice on the way out, each time at a rate that includes a margin. Holding the casino account in the same currency as the bank account removes most of it. Where that is impossible, the conversion rate on the banking page can be compared with the rate the bank quotes.
A few casinos charge for it, aiming at people who use the account to move money rather than to play.
A balance below the minimum for the chosen method cannot be withdrawn, so that money stays in play; the minimums are listed by method.
Many waive the fee for one or two withdrawals a month and charge for any further requests in the same month.
Wallet, card and crypto charges appear in the method's own price list, not in the casino terms, so that list is the only place to see them beforehand.
Some charge a flat amount per payout, others a percentage, and the fee table in the payment terms lists each case.
Mismatched currencies can mean two conversions on the way in and two on the way out, each with a margin built into the rate.