Hi there,
Just a small correction here if anyone in the future comes across this thread and has the same problem.
If you currently have Cloudflare CAAs it must mean you have one or several of the following features enabled: AMP, SXG, Universal SSL.
In this case without sharing too much the affected zone was downgraded to free but for some reason SXG was left enabled but invisible to the user. Then, since the zone was free there was no way to disable it, meaning that nothing the user could do would delete the CAA records.
This made me reconsider my previous statements in this post, and I’ll be redacting some not to induce someone else in error.
I’ve had submitted a correction to the documentation pointed by @epic.network but the fact that this can happen, made me cancel my merge on the documentation until I get a full picture of what happened.
Take care.