Lightsail returning self-signed certificate

I am using a custom domain that I own and attached that to LightSail distribution. As part of the process, I also created a certificate, validated it in my DNS registrar(Namecheap) and then attached it.

But when I make a call to my website:

curl -v https://whatify.io

I see that it is returning a self signed certificate. Below is the relevant output:

* ALPN, offering http/1.1
* successfully set certificate verify locations:
*  CAfile: /etc/ssl/certs/ca-certificates.crt
*  CApath: /etc/ssl/certs
* TLSv1.3 (OUT), TLS handshake, Client hello (1):
* TLSv1.3 (IN), TLS handshake, Server hello (2):
* TLSv1.3 (IN), TLS handshake, Encrypted Extensions (8):
* TLSv1.3 (IN), TLS handshake, Certificate (11):
* TLSv1.3 (OUT), TLS alert, unknown CA (560):
* SSL certificate problem: self signed certificate
* Closing connection 0
curl: (60) SSL certificate problem: self signed certificate
More details here: https://curl.se/docs/sslcerts.html

I can see on the LightSail distribution tab in AWS console that the ceritifcate is valid and in-use. Why is this happening?