In our previous article, it was discussed how Bitcoin is not currency. When it comes to lending, currency can be repaid at a later time on a 1:1 basis. However, money like Bitcoin, or other things like gold or apples, must be repaid according to the fiat value. So if Bitcoin increases in price, less Bitcoin is paid back when the loan is repaid.
Loaning or borrowing at interest is forbidden in the Torah. Even participating in a loan that involves interest, like being a witness, is a violation. If someone cannot repay a loan, it is against Halacha for the debtor to pressure the borrower. It is a violation to pressure borrowers to give collateral, collateral must be willingly given. If the borrower needs their collateral back the debtor must give the collateral back without delay, even without repayment. Finally, if a loan continues for 7 years, then it must be released even without repayment.