I’ve had domains listed by Spamhaus in the past, and getting that resolved was consistently an extremely unpleasant experience.
Spamhaus appears to hate free hosting providers. They tend to say things like “we will only delist your domain if you make sure that no bad content can ever be published on it again”. Which is just impossible when you’re giving our free subdomains to people and not in control of the content being published on it.
So for now, I support the recommendation to just get your own domain name.
Not quite. This listing is far more recent. I know that, because it got listed before half a year ago, which could be resolved then.
This mostly has to do with bad websites being hosted on the domain. Spamhaus is mostly about email, but they also look at malicious links shared in emails.