I was mildly annoyed by the handling of this for domains. I have a personal domain, and now I know that one of the generally service-specific email addresses I've used (most likely with a unique password unless it's Palm levels of old) has been breached with its password. I don't know which one because I don't have a high enough (paid) account.
If I'd realized that jumping through the hoops to get onto the site was just going to tell me I'd need a paid account I'd have saved myself a few minutes. As it was it made the whole experience feel like I fell for a sales email.
The message I got wasn't related to the number of addresses affected (though I've been using this approach for a couple decades), but IIRC regarded whether the datasets in question were free.
If I'd realized that jumping through the hoops to get onto the site was just going to tell me I'd need a paid account I'd have saved myself a few minutes. As it was it made the whole experience feel like I fell for a sales email.