I would've guessed that once it's established that the bug is caused by the app injecting the specified username into the USERINFO portion of a URL without the

I would've guessed that once it's established that the bug is caused by the app injecting the specified username into the USERINFO portion of a URL without the necessary percent-encoding, a workaround (other than using a different client) would be to manually percent-encode the username, i.e., replace the "@" with "%40" ... although this wouldn't work if the app actually did percent-encode an entered "%" despite not encoding an entered "@"!