GitLab credentialsSecret is not working

I'm trying to use this operator to sync groups with a on-premises GitLab instance using token authentication but I'm getting the following error from the controller-manager pod:

2022-09-12T19:37:18.348Z ERROR controller-runtime.manager.controller.groupsync Reconciler error {"reconciler group": "redhatcop.redhat.io", "reconciler kind": "GroupSync", "name": "gitlab-groupsync", "namespace": "group-sync-operator", "error": "GET https://my.internal.gitlab.domain/api/v4/groups: 401 {message: 401 Unauthorized}"}

GroupSync is configured as follow:

apiVersion: redhatcop.redhat.io/v1alpha1
kind: GroupSync
metadata:
name: gitlab-groupsync
namespace: group-sync-operator
spec:
providers:
- gitlab:
credentialsSecret:
kind: Secret
name: gitlab-group-sync
namespace: group-sync-operator
insecure: false
prune: false
url: https://my.internal.gitlab.domain/
name: gitlab

I've tried to access the GitLab api using curl with the same token in gitlab-group-sync secret and got the groups list from GitLab as expected

Group Sync Operator version: 0.0.20
GitLab version: 11.10.4

Start with the controller-manager's GroupSync reconciliation path and how the GitLab credentialsSecret is read. Compare the request authentication with the token that succeeds via curl against the configured on-premises URL. Done means reconciliation authenticates successfully and the groups list syncs without a 401.