How is zakat calculated on cryptocurrencies, such as Bitcoin, especially since their value constantly fluctuates and is not stable?

Cryptocurrencies are subject to the same rulings as fiat money regarding the obligation of Zakat and the applicability of riba (usury/interest). Zakat must be paid on them if they reach the nisab (minimum threshold) either on their own or by being combined with money, gold, or silver, and a hawl (one lunar year) has passed on them. The amount of Zakat is one-quarter of one-tenth (2.5%), and the nisab is estimated at the equivalent of 595 grams of silver. Zakat may be paid from the cryptocurrencies themselves or from their value in fiat currency, gold, or silver on the day Zakat is due. The hawl for these currencies varies depending on how they were acquired: if one acquires them through a gift or mining, the hawl begins from the moment of possession. If one purchases them with money or trade goods that meet the nisab, the hawl begins from the moment of possessing the money or goods. If one purchases them with money that does not meet the nisab, the hawl begins when they reach the nisab. Zakat is paid on the currency along with its profit.