Is it considered an act of disbelief (kufr) to mock a friend who deals with usury (riba) by saying that he is "swimming in blood" or that his "bank account is blood," knowing that the intention was not to mock the hadith but rather the friend himself?

It is established that the usurer is tormented in a river like blood. Mocking a usurer and likening his money to blood is not disbelief (kufr), because disbelief through mockery applies to Allah, His Messenger, or His religion. Mocking a Muslim's person or his wrong actions does not cause disbelief. A Muslim must refrain from ridiculing Allah's servants, whether they are obedient or disobedient, because it is among the bad habits forbidden in His, the Almighty's, saying: "O you who have believed, let not a people ridicule [another] people." Joking with what is mentioned in the texts of warning (against sin) contradicts compassion and advice, and may increase his disobedience or lead him to ridicule the religion. This kind of joking should be abandoned, and one should instead focus on inviting your companion and advising him with wisdom and good counsel.