[release-next] (release 1.20) Supported Releases

[maelvls]

Update: Closing in favor of #2007.

Part of of the "Prepare the Freeze and Bump Versions" step from the cert-manager release process (step 5, for final + patch releases).

[cert-manager-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign jakexks for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[netlify]

✅ Deploy Preview for cert-manager ready!

Built without sensitive environment variables

Name	Link
🔨 Latest commit	5299692
🔍 Latest deploy log	https://app.netlify.com/projects/cert-manager/deploys/69b14bbdf817ca0007afca2a
😎 Deploy Preview	https://deploy-preview-2005--cert-manager.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[Copilot]

Pull request overview

Updates the releases documentation to reflect the cert-manager v1.20.0 release and the resulting supported/EOL release windows.

Changes:

• Adds cert-manager 1.20 to the supported releases table and removes 1.18 from supported.
• Updates the “Upcoming releases” table to include 1.21.
• Moves 1.18 into the EOL table and updates the “Oldest Kubernetes Release” snapshot date.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

This release entry is the only one in these tables that is not formatted as a link (e.g., || [1.20][] | ...). Consider changing it to || [1.21][] | ... (and ensuring the corresponding reference is defined) to keep navigation/formatting consistent across the doc.

Suggested change

	| 1.21 | Jun 24, 2026 | Release of 1.23 | 1.33 → 1.36 / 4.20 → 4.22 | 1.33 → 1.36 |
	| [1.21][] | Jun 24, 2026 | Release of 1.23 | 1.33 → 1.36 / 4.20 → 4.22 | 1.33 → 1.36 |
	[1.21]: https://cert-manager.io/docs/release-notes/release-1.21/

[maelvls]

Closing in favor of #2007.