If selected "Delete all operand instances ..." checkbox, cert-manager operator is stuck in being uninstalled. If don't select it, and try Uninstall again, then no such issue.

cert-manager installed with cert-manager-operator-bundle-container-v1.10.2-18 on cluster of payload 4.13.0-0.nightly-2023-03-09-162945.

Always

1. In the OpenShift Console, install cert-manager operator of bundle version v1.10.2-18.
2. Wait the installation completes. Check operator, operand pods and CSV, all are in good status. Test selfsigned issuer and cert with it, functions are good.

Save things:
$ oc get po -n cert-manager-operator
NAME                                                        READY   STATUS    RESTARTS   AGE
cert-manager-operator-controller-manager-768866b856-rz6h5   2/2     Running   0          2m32s

$ oc get certmanager cluster -o yaml > certmanager-before-uninstall.yaml

3. In the OpenShift Console, in the "Installed Operators" page, follow https://docs.openshift.com/container-platform/4.12/operators/admin/olm-deleting-operators-from-cluster.html the "Deleting Operators from a cluster using the web console" section, click "Uninstall Operator", it shows a dialog:
"Operator cert-manager Operator for Red Hat OpenShift will be removed from cert-manager-operator. Select the checkbox below to also remove all Operands associated with this Operator. If your Operator configured off-cluster resources, these will continue to run and require manual cleanup".

Select the checkbox, click Uninstall.

3. Wait. Check previous dialog, it is stuck and showing "Cleaning up operand instances...Remaining Operands: 1 of 1".

Check certmanager again, it appears automatically recreated:
$ oc get certmanager cluster -o yaml > certmanager-during-still-uninstall.yaml
$ diff certmanager-before-uninstall.yaml certmanager-during-still-uninstall.yaml

$ diff certmanager-before-uninstall.yaml certmanager-during-still-uninstall.yaml
4c4
<   creationTimestamp: "2023-03-10T09:46:48Z"
---
>   creationTimestamp: "2023-03-10T09:50:05Z"
7d6
<   - cert-manager-operator.operator.openshift.io/cert-manager-webhook-deployment
8a8
>   - cert-manager-operator.operator.openshift.io/cert-manager-webhook-deployment
11,12c11,12
<   resourceVersion: "133350"
<   uid: 6859cc65-78ba-434d-87a5-500e4dc3b107
---
>   resourceVersion: "134215"
>   uid: 3a05afe2-82e1-4bfe-aba2-9a30d8ed6c7b
21,37c21
<   - lastTransitionTime: "2023-03-10T09:47:06Z"
<     status: "True"
<     type: cert-manager-webhook-deploymentAvailable
<   - lastTransitionTime: "2023-03-10T09:47:06Z"
<     status: "False"
<     type: cert-manager-webhook-deploymentProgressing
<   - lastTransitionTime: "2023-03-10T09:47:00Z"
<     status: "True"
<     type: cert-manager-cainjector-deploymentAvailable
<   - lastTransitionTime: "2023-03-10T09:47:00Z"
<     status: "False"
<     type: cert-manager-cainjector-deploymentProgressing
<   - lastTransitionTime: "2023-03-10T09:46:48Z"
<     reason: AsExpected
<     status: "False"
<     type: cert-manager-webhook-deploymentDegraded
<   - lastTransitionTime: "2023-03-10T09:47:30Z"
---
>   - lastTransitionTime: "2023-03-10T09:50:07Z"
40c24
<   - lastTransitionTime: "2023-03-10T09:47:30Z"
---
>   - lastTransitionTime: "2023-03-10T09:50:07Z"

If selected "Delete all operand instances ..." checkbox, cert-manager operator is stuck in being uninstalled. If don't select this checkbox, then no such issue.

Given the checkbox is provided, if users select it when do Uninstall, cert-manager operator should be able to be uninstalled instead of being stuck in uninstalling.