AWS CLI: unable to get issuer certificate - amazon-s3

Question

I have deployed an AWS S3 compatible solution on which I configured signed certificates for the API endpoint.
Now, if I try to list some buckets, I get:
$ aws s3 ls s3://bucket --endpoint-url https://s3.endpoint --ca-bundle /etc/ssl/certs/ca-certificates.crt
SSL validation failed for https://s3.endpoint/bucket?list-type=2&prefix=&delimiter=%2F&encoding-type=url
[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get issuer certificate (_ssl.c:1125)
But if I curl the same S3 endpoint from the same machine, I get SSL certificate verify ok:
curl https://s3.endpoint -v
* Trying 192.168.0.1:443...
* TCP_NODELAY set
* Connected to s3.endpoint (192.168.0.1) port 443 (#0)
* ALPN, offering h2
* 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):
* TLSv1.2 (IN), TLS handshake, Certificate (11):
* TLSv1.2 (IN), TLS handshake, Server key exchange (12):
* TLSv1.2 (IN), TLS handshake, Server finished (14):
* TLSv1.2 (OUT), TLS handshake, Client key exchange (16):
* TLSv1.2 (OUT), TLS change cipher, Change cipher spec (1):
* TLSv1.2 (OUT), TLS handshake, Finished (20):
* TLSv1.2 (IN), TLS handshake, Finished (20):
* SSL connection using TLSv1.2 / ECDHE-RSA-AES256-GCM-SHA384
* ALPN, server accepted to use http/1.1
* Server certificate:
* subject: C=my-C; ST=my-ST; L=my-L; O=my-O; OU=my-OU; CN=s3.endpoint; emailAddress=my-email
* start date: Jun 28 11:03:53 2021 GMT
* expire date: Jun 28 11:03:53 2023 GMT
* subjectAltName: host "s3.endpoint" matched cert's "s3.endpoint"
* issuer: C=issuer-C; O=issuer-O; OU=issuer-OU; CN=issuer-CN
* SSL certificate verify ok.
> GET / HTTP/1.1
> Host: s3.endpoint
> User-Agent: curl/7.68.0
> Accept: */*
>
...
Is there something wrong with my aws command ?
$ aws --version
aws-cli/2.2.14 Python/3.8.8 Linux/5.4.0-73-generic exe/x86_64.ubuntu.20 prompt/off