I think OP means that you have to make sure you don't forget to/neglect to renew it and make sure you don't accidentally lose the domain for any reason.

Thank you for the clarification. I use a dedicated card for domain hosting (with autorenewal enabled) to prevent this specific issue but I recognize most people likely don't do the same.

spot on, basically you now have to worry about the domain being lost or hijacked also. for me, the flexibility to change email providers behind a domain is worth it though