Login to OCP -> Developer Perspective > Add > All services (catalog) > search NGINX > use Templates > Instantiate Template

Looking on this page you will see that under Git Repo URL check parameters: "name": "NGINX_VERSION", value should be: "value": "1.20-ubi8" but template uses :
NGINX Version - 1.20-el8 (which is wrong)

sample ImageStream from this in my namespace:
=================================================================
kind: ImageStream
apiVersion: image.openshift.io/v1
metadata:
annotations:
description: Keeps track of changes in the application image
name: nginx-example
namespace: mmv
labels:
template: nginx-example
template.openshift.io/template-instance-owner: ea96d4e0-84d4-4faf-ace3-9030d967a5de
spec:
lookupPolicy:
local: false
status:
dockerImageRepository: 'image-registry.openshift-image-registry.svc:5000/mmv/nginx-example'

So, the ImageStream in openshift namespace:
=================================================================
kind: ImageStream
apiVersion: image.openshift.io/v1
metadata:
annotations:
openshift.io/display-name: Nginx HTTP server and a reverse proxy (nginx)
samples.operator.openshift.io/version: 4.12.31
name: nginx
namespace: openshift
labels:
samples.operator.openshift.io/managed: 'true'
spec:
lookupPolicy:
local: false
tags:

• name: 1.20-ubi7
  annotations:
  description: >-
  Build and serve static content via Nginx HTTP server and a reverse
  proxy (nginx) on RHEL 7. For more information about using this builder
  image, including OpenShift considerations, see
  https://github.com/sclorg/nginx-container/blob/master/1.20/README.md
  .
  iconClass: icon-nginx
  openshift.io/display-name: Nginx HTTP server and a reverse proxy 1.20 (UBI 7)
  openshift.io/provider-display-name: 'Red Hat, Inc.'
  sampleRepo: '
  https://github.com/sclorg/nginx-ex.git
  '
  supports: nginx
  tags: 'builder,nginx'
  version: '1.20'
  from:
  kind: DockerImage
  name: 'registry.redhat.io/ubi7/nginx-120:latest'
  generation: 2
  importPolicy:
  importMode: Legacy
  referencePolicy:
  type: Local
• name: 1.20-ubi8
  annotations:
  description: >-
  Build and serve static content via Nginx HTTP server and a reverse
  proxy (nginx) on RHEL 8. For more information about using this builder
  image, including OpenShift considerations, see
  https://github.com/sclorg/nginx-container/blob/master/1.20/README.md
  .
  iconClass: icon-nginx
  openshift.io/display-name: Nginx HTTP server and a reverse proxy 1.20 (UBI 8)
  openshift.io/provider-display-name: 'Red Hat, Inc.'
  sampleRepo: '
  https://github.com/sclorg/nginx-ex.git
  '
  supports: nginx
  tags: 'builder,nginx'
  version: '1.20'
  from:
  kind: DockerImage
  name: 'registry.redhat.io/ubi8/nginx-120:latest'
  generation: 2
  importPolicy:
  importMode: Legacy
  referencePolicy:
  type: Local
• name: 1.20-ubi9
  annotations:
  description: >-
  Build and serve static content via Nginx HTTP server and a reverse
  proxy (nginx) on RHEL 8. For more information about using this builder
  image, including OpenShift considerations, see
  https://github.com/sclorg/nginx-container/blob/master/1.20/README.md
  .
  iconClass: icon-nginx
  openshift.io/display-name: Nginx HTTP server and a reverse proxy 1.20 (UBI 9)
  openshift.io/provider-display-name: 'Red Hat, Inc.'
  sampleRepo: '
  https://github.com/sclorg/nginx-ex.git
  '
  supports: nginx
  tags: 'builder,nginx'
  version: '1.20'
  from:
  kind: DockerImage
  name: 'registry.redhat.io/ubi9/nginx-120:latest'
  generation: 2
  importPolicy:
  importMode: Legacy
  referencePolicy:
  type: Local
• name: latest
  annotations:
  description: >-
  Build and serve static content via Nginx HTTP server and a reverse
  proxy (nginx) on RHEL. For more information about using this builder
  image, including OpenShift considerations, see
  https://github.com/sclorg/nginx-container/blob/master/1.20/README.md
  .

WARNING: By selecting this tag, your application will automatically
update to use the latest version of Nginx available on OpenShift,
including major version updates.
iconClass: icon-nginx
openshift.io/display-name: Nginx HTTP server and a reverse proxy (Latest)
openshift.io/provider-display-name: 'Red Hat, Inc.'
sampleRepo: '
https://github.com/sclorg/nginx-ex.git
'
supports: nginx
tags: 'builder,nginx'
from:
kind: ImageStreamTag
name: 1.20-ubi8
generation: 1
importPolicy:
importMode: Legacy
referencePolicy:
type: Local
status:
dockerImageRepository: 'image-registry.openshift-image-registry.svc:5000/openshift/nginx'
tags:

• tag: 1.20-ubi7
  items:
• created: '2023-11-27T00:28:31Z'
  dockerImageReference: >-
  registry.redhat.io/ubi7/nginx-120@sha256:608c4b97a936745494f698b2b45f347f3b8ee241fa1f2b52d5dfd8b205ff7783
  image: >-
  sha256:608c4b97a936745494f698b2b45f347f3b8ee241fa1f2b52d5dfd8b205ff7783
  generation: 2
• tag: 1.20-ubi8
  items:
• created: '2023-11-27T00:28:31Z'
  dockerImageReference: >-
  registry.redhat.io/ubi8/nginx-120@sha256:77076b4757a344ccc3d133de9c44d7d2af0935e19d4e9cefbd1b42815d08df84
  image: >-
  sha256:77076b4757a344ccc3d133de9c44d7d2af0935e19d4e9cefbd1b42815d08df84
  generation: 2
• tag: 1.20-ubi9
  items:
• created: '2023-11-27T00:28:31Z'
  dockerImageReference: >-
  registry.redhat.io/ubi9/nginx-120@sha256:66d0fc66e59b22892977d054e311403e2294b1bed00f87ada9744990f5bc29b6
  image: >-
  sha256:66d0fc66e59b22892977d054e311403e2294b1bed00f87ada9744990f5bc29b6
  generation: 2
• tag: latest
  items:
• created: '2023-11-27T00:28:31Z'
  dockerImageReference: >-
  registry.redhat.io/ubi8/nginx-120@sha256:77076b4757a344ccc3d133de9c44d7d2af0935e19d4e9cefbd1b42815d08df84
  image: >-
  sha256:77076b4757a344ccc3d133de9c44d7d2af0935e19d4e9cefbd1b42815d08df84
  generation: 2
  =================================================================

If customer delete the template from openshift ( labels: samples.operator.openshift.io/managed: 'true' ) it reapears but still "wrong".