Why isn't Google Indexing Discourse? SEO concerns

[Jagster (Jakke Lehtonen)]

Can it be done this way?

Search engines now blocked from indexing non-canonical pages

Discourse will now reply with a X-Robots-Tag: noindex header when the requested page isn’t the canonical page for a resource. While Discourse uses an automatic scrolling design for both topic lists and topics, this isn’t what we show search engine crawlers, like GoogleBot. Search engines see paginated topics, with 20 posts in each page. However, since users can link to specific posts in their own posts and will do so using the /t/title/topic_id/post_id URL format, those will be picked by the cr…

Or using plugin, as one dev told me — for me she’s asking to high price, though. Or using Varnish instead?

I really don’t know anything else that is told to me. All I know for sure is noindex is right now harming SEO on my forum.