Core output, SEO plugin and theme head
In the relevant SEO plugin, check both data sets: the starting page and the canonical target. A category with a conscious noindex is not a suitable main contribution.
On a single content page, check if WordPress Core, SEO plugin, and theme each output canonicals. For archives, a different logic may apply than for contributions. Do not blindly remove the core function, but first determine the leading source.
Where to check the setting in WordPress
Open the head of a published single view and search for rel=canonical. Assign the output to the core call rel_canonical, the active SEO plugin or your own theme snippet. A second manual output in the header does not fix an incorrect plugin value.
Example of this specific finding
Illustrative control case: A publicly advertised product variant refers to a main product with noindex. If the main product is to appear in the search, its exclusion contradicts this intention.
follow-up audit in WordPress
Compare a post, a static page and an archive. The additional tag comes from a theme snippet, the change of which is first checked in a test environment.
For the main product and variant separately decide which URL should be indexed. Only then canonical and indexing requirements be corrected together.
Derogations and scope
Noindex on the target does not blindly remove: the main product may have been deliberately withdrawn. Another appropriate content or removal of the variant may be required.
Related: WordPress with classic or block theme. SEO plugins and page builders are different; there is no universal menu path for all installations.
Classify the general error
Definition, system-independent causes and further correction examples: Set indexing intent for both parties