CertManager: certificate signed by unknown authority

[jaro-sagan]

Hi all, I would like to install cert-manager using LetsEncrypt to my local k8s cluster (created via docker desktop app). I have been following this guide and I'm facing an issue with ClusterIssuer

The ClusterIssuer is defined as:

apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
  name: letsencrypt
spec:
  acme:
    # The ACME server URL
    server: https://acme-v02.api.letsencrypt.org/directory
    # Email address used for ACME registration
    email: some@email.com
    # Name of a secret used to store the ACME account private key
    privateKeySecretRef:
      name: letsencrypt
    # Enable the HTTP-01 challenge provider
    solvers:
      - http01:
          ingress:
            ingressClassName: nginx

And here is the output of describe:

Status:
  Acme:
  Conditions:
    Last Transition Time:  2024-02-16T13:36:32Z
    Message:               Failed to register ACME account: Get https://acme-v02.api.letsencrypt.org/directory: tls: failed to verify certificate: x509: certificate signed by unknown authority
    Observed Generation:   1
    Reason:                ErrRegisterACMEAccount
    Status:                False
    Type:                  Ready
Events:
  Type     Reason         Age                   From                         Message
  ----     ------         ----                  ----                         -------
  Warning  ErrInitIssuer  3m54s (x13 over 38m)  cert-manager-clusterissuers  Error initializing issuer: Get https://acme-v02.api.letsencrypt.org/directory: tls: failed to verify certificate: x509: certificate signed by unknown authority

Could you pls help me to resolve the issue or point me to some resources that could help with that?

Thank you.