They're calling comments DNS record attributes.
I first saw comments on Porkbun, as a way to add context for cryptic DNS records. As I began using Cloudflare as a nameserver for more domains, I missed the comments feature.
Comments are a real quality-of-life improvement, if you have more than a handful of records.
Bonus: looks like Cloudflare is shaping up to use DNS record attributes for functionality like filtering.