The ones used by freenom were particularly abused:

https://prezkennedy.com/2026/01/15/the-free-domain-trap-the-...

> Freenom’s terms of service allowed them to “cancel” a free domain at any time without warning. Users reported for years that as soon as their free site started getting significant traffic (and becoming valuable), Freenom would reclaim the domain and fill it with ads, effectively hijacking the user’s hard work.