I've been using Cloudflare CDN and DNS, the IPs that I've been inserting into its DNS manager were masked/hidden for DNS checkers (e.g., https://www.whatsmydns.net/).
Is there a way to hide the IP on AWS Route53?
So far, I didn't find a way to achieve that.
Hiding IP is a CDN feature, not really a DNS feature. Note that the only IPs hidden in Cloudflare are the ones with the "orange cloud", i.e. the ones that have CDN caching enabled.
Route53 is a DNS service only. Amazon's CloudFront would basically hide the IP for you, if you used CloudFront in front of your service, and didn't otherwise publish your server IPs in any DNS records.