docs: add faq entry for marshaling error

[nitishfy]

Closes #25815

Checklist:

• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this does not need to be in the release notes.
• The title of the PR states what changed and the related issues number (used for the release note).
• The title of the PR conforms to the Title of the PR
• I've included "Closes [ISSUE #]" or "Fixes [ISSUE #]" in the description to automatically close the associated issue.
• I've updated both the CLI and UI to expose my feature, or I plan to submit a second PR with them.
• Does this PR require documentation updates?
• I've updated documentation as required by this PR.
• I have signed off all my commits as required by DCO
• I have written unit and/or e2e tests for my change. PRs without these are unlikely to be merged.
• My build is green (troubleshooting builds).
• My new feature complies with the feature status guidelines.
• I have added a brief description of why this PR is necessary and/or what this PR solves.
• Optional. My organization is added to USERS.md.
• Optional. For bug fixes, I've indicated what older releases this fix should be cherry-picked into (this may or may not happen depending on risk/complexity).

[bunnyshell]

❌ Preview Environment deleted from Bunnyshell

Available commands (reply to this comment):

• 🚀 /bns:deploy to deploy the environment

[rumstead]

Do we know why the auto generated redis secret is containing binary data?

[nitishfy]

I've not researched about it yet, will do it and let you know.

[nitishfy]

The Redis password generator only uses printable ASCII characters, so it should not generate binary / non-UTF-8 data.

The clusters where this breaks likely already had an existing Redis secret with non-UTF-8 bytes (possibly created by an older Argo CD version). IMO, Kubernetes 1.34 surfaces this more strictly, causing pods to fail when a secret with non-UTF-8 data is referenced. So this doesn’t appear to be a new secret generation producing binary data, but rather existing invalid secret contents being exposed by stricter validation.