Actions validate the keys in with: against their declared inputs. Passing an undeclared key (a typo or a removed input) triggers a warning listing the valid inputs.
What this error means
A step warns "Unexpected input(s) '<key>', valid inputs are [...]" and the intended option silently has no effect because the action never received it.
github-actions
Warning: Unexpected input(s) 'node_versions', valid inputs are ['always-auth', 'node-version', 'cache']
Common causes
Misspelled input name
The with: key does not match a declared input (node_versions vs node-version), so it is ignored.
Input from a different action version
The key existed in another version of the action but not the one referenced.
How to fix it
Match keys to the action's declared inputs
Read the listed valid inputs in the warning.
Correct the spelling/casing of the with: key.
Confirm the input exists in the pinned action version.