Does IP reputation carry across domains?

Partially. IP reputation is IP specific, but domains sharing an IP share reputation risk. If multiple domains send from one IP, their collective behavior affects that IP's reputation.

Your domain reputation is separate from IP reputation. You can have good domain reputation despite shared IP issues, or vice versa. Providers evaluate both.

On dedicated IPs, you control IP reputation entirely. On shared IPs, pool quality affects your delivery even if your own practices are good.