In my opinion, don't involve a tier. You can't report a problem that has no solution: it's nobody's job to change the toxic co-worker. Go talk to him, tell him

In my opinion, don't involve a tier. You can't report a problem that has no solution: it's nobody's job to change the toxic co-worker. Go talk to him, tell him how he makes you feel (not "you do this, you do that", but "I feel like shit when you say X"). And ask him to be kind/patient to less experienced devs. Make him feel important by requesting his mentorship instead of acid complaints. Tell him he can help empower others instead of belittling them. Talking to a manager will only make things worse.