Fastmail offers per-service generated addresses. I think it's kind of fascinating to watch my email address that went solely to my local credit union start sending me spam somewhat related to my employer.
Fastmail allows for aliasing too - username@domain.tld -> bank@username.domain.tld, retailer@username.domain.tld, etc. Pretty convenient. I use that feature pretty often and I can only recall one instance which seemed to indicate my address was sold to spammers. It’s more useful for organizing incoming mail, like plus-aliasing in gmail.