Нужно указать параметр proxied = true:
curl -X POST "https://api.cloudflare.com/client/v4/zones/023e105f4ecef8ad9ca31a8372d0c353/dns_records" \
-H "X-Auth-Email: user@example.com" \
-H "X-Auth-Key: c2547eb745079dac9320b638f5e225cf483cc5cfdda41" \
-H "Content-Type: application/json" \
--data '{"type":"A","name":"example.com","content":"127.0.0.1","ttl":120,"priority":10,"proxied":false}'
Пробовал по всякому:
"proxied",true
"proxied",1
"proxied","true"
но всегда возвращает "Invalid 'proxied' value, must be a boolean"