Is it permissible to receive a salary from working at a usurious bank during the summer, knowing that the employee's bank account is with an Islamic bank?

It is not permissible to work in a Riba-based bank, because it involves witnessing evil and cooperating in sin. The Prophet, peace and blessings be upon him, cursed the one who consumes Riba, the one who pays it, its scribe, and its two witnesses. Therefore, working in it is forbidden, even for a short period, and the salary resulting from it is unlawful.