Borrowing crypto assets is no different than borrowing from a traditional lender. The IRS does not consider a loan to be taxable income because it must be repaid. On the other hand, if a crypto loan with an initial USD value of over $600 is forgiven, you should receive a 1099-C for cancellation of debt (COD) income, which is taxable. If the loan provider requires an exchange of crypto for you to get the loan — for example, swapping ETH for cETH to get a loan in Compound (referring to https://compound.finance/) — a conservative approach would be to report the gain or loss, if any, that results from that transaction.